Explain what this code does. Then, convert this recursive function to an iterative one, making explicit the cubic work that's being done. The functions should return exactly the same output but the iterative one should be faster. Call your function `solve_iterative` and match the type signature of the original function. @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value
Explain what this code does. Then, convert this recursive function to an iterative one, making explicit the cubic work that's being done. The functions should return exactly the same output but the iterative one should be faster. Call your function `solve_iterative` and match the type signature of the original function. @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function aims to minimize the sum of squared distances from points in a graph to selected lines, subject to constraints. Args: graph (list of int): Represents the positions of points on a line. lines_left (int): The remaining number of lines allowed to be used. distance_since_last (int): The distance from the last selected line to the current point. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices indicating the selected line positions in the original graph. """ if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of solve_dp. This function utilizes dynamic programming to solve the problem iteratively. It creates a 3D table `dp` to store calculated results for subproblems. Each cell in `dp` corresponds to a state defined by (graph index, lines left, distance since last line). """ n = len(graph) dp = [[[None for _ in range(11)] for _ in range(lines_left + 1)] for _ in range(n + 1)] # Base cases for i in range(n + 1): for j in range(11): dp[i][0][j] = (0, []) if i == 0 else (1e9, []) # Fill the dp table iteratively for i in range(1, n + 1): for j in range(1, lines_left + 1): for k in range(11): dp[i][j][k] = dp[i - 1][j][k] # Initialize with not taking the line if k > 0: dp[i][j][k] = min(dp[i][j][k], dp[i - 1][j][k - 1]) # Consider not taking the line if j > 0: sub, how = dp[i - 1][j - 1][0] sub += graph[i - 1] + (k - 8) ** 2 dp[i][j][k] = min(dp[i][j][k], (sub, how + [i])) return dp[n][lines_left][distance_since_last] |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function aims to minimize the sum of squared distances from points in a graph to selected lines, subject to constraints. Args: graph (list of int): Represents the positions of points on a line. lines_left (int): The remaining number of lines allowed to be used. distance_since_last (int): The distance from the last selected line to the current point. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices indicating the selected line positions in the original graph. """ if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of solve_dp. This function utilizes dynamic programming to solve the problem iteratively. It creates a 3D table `dp` to store calculated results for subproblems. Each cell in `dp` corresponds to a state defined by (graph index, lines left, distance since last line). """ n = len(graph) dp = [[[None for _ in range(11)] for _ in range(lines_left + 1)] for _ in range(n + 1)] # Base cases for i in range(n + 1): for j in range(11): dp[i][0][j] = (0, []) if i == 0 else (1e9, []) # Fill the dp table iteratively for i in range(1, n + 1): for j in range(1, lines_left + 1): for k in range(11): dp[i][j][k] = dp[i - 1][j][k] # Initialize with not taking the line if k > 0: dp[i][j][k] = min(dp[i][j][k], dp[i - 1][j][k - 1]) # Consider not taking the line if j > 0: sub, how = dp[i - 1][j - 1][0] sub += graph[i - 1] + (k - 8) ** 2 dp[i][j][k] = min(dp[i][j][k], (sub, how + [i])) return dp[n][lines_left][distance_since_last] |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function aims to minimize the sum of squared distances from points in a graph to selected lines, subject to constraints. Args: graph (list of int): Represents the positions of points on a line. lines_left (int): The remaining number of lines allowed to be used. distance_since_last (int): The distance from the last selected line to the current point. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices indicating the selected line positions in the original graph. """ if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of solve_dp. This function utilizes dynamic programming to solve the problem iteratively. It creates a 3D table `dp` to store calculated results for subproblems. Each cell in `dp` corresponds to a state defined by (graph index, lines left, distance since last line). """ n = len(graph) dp = [[[None for _ in range(11)] for _ in range(lines_left + 1)] for _ in range(n + 1)] # Base cases for i in range(n + 1): for j in range(11): dp[i][0][j] = (0, []) if i == 0 else (1e9, []) # Fill the dp table iteratively for i in range(1, n + 1): for j in range(1, lines_left + 1): for k in range(11): dp[i][j][k] = dp[i - 1][j][k] # Initialize with not taking the line if k > 0: dp[i][j][k] = min(dp[i][j][k], dp[i - 1][j][k - 1]) # Consider not taking the line if j > 0: sub, how = dp[i - 1][j - 1][0] sub += graph[i - 1] + (k - 8) ** 2 dp[i][j][k] = min(dp[i][j][k], (sub, how + [i])) return dp[n][lines_left][distance_since_last] answer = 0 import random mylist = list(range(100)) random.shuffle(mylist) from functools import lru_cache @lru_cache(maxsize=None) def my_solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, my_solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = my_solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value answer = solve_iterative(tuple(mylist), len(mylist)//8, 4) expected = my_solve_dp(tuple(mylist), len(mylist)//8, 4) assert answer == expected, f'Wrong answer; got {answer} instead of {expected}' print('All tests passed') |
Traceback (most recent call last):
File "/usr/src/app/main.py", line 98, in <module>
answer = solve_iterative(tuple(mylist), len(mylist)//8, 4)
File "/usr/src/app/main.py", line 64, in solve_iterative
dp[i][j][k] = min(dp[i][j][k], (sub, how + [i]))
TypeError: '<' not supported between instances of 'tuple' and 'NoneType'
Testing if the previous output contains the string All tests passed
: False
Resulting in output: True
Explain what this code does. Then, convert this recursive function to an iterative one, making explicit the cubic work that's being done. The functions should return exactly the same output but the iterative one should be faster. Call your function `solve_iterative` and match the type signature of the original function. @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value
Explain what this code does. Then, convert this recursive function to an iterative one, making explicit the cubic work that's being done. The functions should return exactly the same output but the iterative one should be faster. Call your function `solve_iterative` and match the type signature of the original function. @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function aims to minimize the sum of squared distances from each point in a graph to a set of 'lines'. It uses dynamic programming to explore different combinations of lines. Args: graph (list of int): Represents the points on a line, with each element being the distance from the origin. lines_left (int): The number of lines that can still be placed. distance_since_last (int): The distance from the last placed line to the current point being considered. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in the graph where lines were placed to achieve the minimum. """ if len(graph) < lines_left: return 1e9, [] # Not enough points for remaining lines if lines_left == 0 and len(graph) == 0: return 0, [] # Base case: no points, no lines left # Option 1: Don't place a line at the current point value = (1e9, []) # Initialize with a large value if distance_since_last < 10: # Check if placing a line is allowed based on distance value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # Option 2: Place a line at the current point if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) # Recursively explore placing a line sub += graph[0] + (distance_since_last-8)**2 # Calculate cost with the placed line value = min(value, (sub, how + [len(graph)])) # Update if this placement is better return value def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of solve_dp, using a 3D array for memoization. Args: graph (list of int): Represents the points on a line. lines_left (int): The number of lines that can still be placed. distance_since_last (int): The distance from the last placed line. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in the graph where lines were placed. """ n = len(graph) dp = [[[None for _ in range(distance_since_last + 1)] for _ in range(lines_left + 1)] for _ in range(n + 1)] # Initialize base cases for i in range(n + 1): for j in range(lines_left + 1): for k in range(distance_since_last + 1): if i < j: dp[i][j][k] = (1e9, []) elif j == 0 and i == 0: dp[i][j][k] = (0, []) # Fill the dp table iteratively for i in range(1, n + 1): for j in range(1, min(i + 1, lines_left + 1)): for k in range(distance_since_last + 1): # Option 1: Don't take the line value = (1e9, []) if k < 10: value = dp[i - 1][j][k + 1] # Option 2: Take the line sub, how = dp[i - 1][j - 1][0] sub += graph[i - 1] + (k - 8) ** 2 value = min(value, (sub, how + [i])) dp[i][j][k] = value return dp[n][lines_left][0] # Return the result from the last cell |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function aims to minimize the sum of squared distances from each point in a graph to a set of 'lines'. It uses dynamic programming to explore different combinations of lines. Args: graph (list of int): Represents the points on a line, with each element being the distance from the origin. lines_left (int): The number of lines that can still be placed. distance_since_last (int): The distance from the last placed line to the current point being considered. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in the graph where lines were placed to achieve the minimum. """ if len(graph) < lines_left: return 1e9, [] # Not enough points for remaining lines if lines_left == 0 and len(graph) == 0: return 0, [] # Base case: no points, no lines left # Option 1: Don't place a line at the current point value = (1e9, []) # Initialize with a large value if distance_since_last < 10: # Check if placing a line is allowed based on distance value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # Option 2: Place a line at the current point if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) # Recursively explore placing a line sub += graph[0] + (distance_since_last-8)**2 # Calculate cost with the placed line value = min(value, (sub, how + [len(graph)])) # Update if this placement is better return value def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of solve_dp, using a 3D array for memoization. Args: graph (list of int): Represents the points on a line. lines_left (int): The number of lines that can still be placed. distance_since_last (int): The distance from the last placed line. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in the graph where lines were placed. """ n = len(graph) dp = [[[None for _ in range(distance_since_last + 1)] for _ in range(lines_left + 1)] for _ in range(n + 1)] # Initialize base cases for i in range(n + 1): for j in range(lines_left + 1): for k in range(distance_since_last + 1): if i < j: dp[i][j][k] = (1e9, []) elif j == 0 and i == 0: dp[i][j][k] = (0, []) # Fill the dp table iteratively for i in range(1, n + 1): for j in range(1, min(i + 1, lines_left + 1)): for k in range(distance_since_last + 1): # Option 1: Don't take the line value = (1e9, []) if k < 10: value = dp[i - 1][j][k + 1] # Option 2: Take the line sub, how = dp[i - 1][j - 1][0] sub += graph[i - 1] + (k - 8) ** 2 value = min(value, (sub, how + [i])) dp[i][j][k] = value return dp[n][lines_left][0] # Return the result from the last cell |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function aims to minimize the sum of squared distances from each point in a graph to a set of 'lines'. It uses dynamic programming to explore different combinations of lines. Args: graph (list of int): Represents the points on a line, with each element being the distance from the origin. lines_left (int): The number of lines that can still be placed. distance_since_last (int): The distance from the last placed line to the current point being considered. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in the graph where lines were placed to achieve the minimum. """ if len(graph) < lines_left: return 1e9, [] # Not enough points for remaining lines if lines_left == 0 and len(graph) == 0: return 0, [] # Base case: no points, no lines left # Option 1: Don't place a line at the current point value = (1e9, []) # Initialize with a large value if distance_since_last < 10: # Check if placing a line is allowed based on distance value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # Option 2: Place a line at the current point if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) # Recursively explore placing a line sub += graph[0] + (distance_since_last-8)**2 # Calculate cost with the placed line value = min(value, (sub, how + [len(graph)])) # Update if this placement is better return value def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of solve_dp, using a 3D array for memoization. Args: graph (list of int): Represents the points on a line. lines_left (int): The number of lines that can still be placed. distance_since_last (int): The distance from the last placed line. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in the graph where lines were placed. """ n = len(graph) dp = [[[None for _ in range(distance_since_last + 1)] for _ in range(lines_left + 1)] for _ in range(n + 1)] # Initialize base cases for i in range(n + 1): for j in range(lines_left + 1): for k in range(distance_since_last + 1): if i < j: dp[i][j][k] = (1e9, []) elif j == 0 and i == 0: dp[i][j][k] = (0, []) # Fill the dp table iteratively for i in range(1, n + 1): for j in range(1, min(i + 1, lines_left + 1)): for k in range(distance_since_last + 1): # Option 1: Don't take the line value = (1e9, []) if k < 10: value = dp[i - 1][j][k + 1] # Option 2: Take the line sub, how = dp[i - 1][j - 1][0] sub += graph[i - 1] + (k - 8) ** 2 value = min(value, (sub, how + [i])) dp[i][j][k] = value return dp[n][lines_left][0] # Return the result from the last cell answer = 0 import random mylist = list(range(100)) random.shuffle(mylist) from functools import lru_cache @lru_cache(maxsize=None) def my_solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, my_solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = my_solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value answer = solve_iterative(tuple(mylist), len(mylist)//8, 4) expected = my_solve_dp(tuple(mylist), len(mylist)//8, 4) assert answer == expected, f'Wrong answer; got {answer} instead of {expected}' print('All tests passed') |
Traceback (most recent call last):
File "/usr/src/app/main.py", line 114, in <module>
answer = solve_iterative(tuple(mylist), len(mylist)//8, 4)
File "/usr/src/app/main.py", line 72, in solve_iterative
value = dp[i - 1][j][k + 1]
IndexError: list index out of range
Testing if the previous output contains the string All tests passed
: False
Resulting in output: True
Explain what this code does. Then, convert this recursive function to an iterative one, making explicit the cubic work that's being done. The functions should return exactly the same output but the iterative one should be faster. Call your function `solve_iterative` and match the type signature of the original function. @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value
Explain what this code does. Then, convert this recursive function to an iterative one, making explicit the cubic work that's being done. The functions should return exactly the same output but the iterative one should be faster. Call your function `solve_iterative` and match the type signature of the original function. @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function aims to minimize the sum of squared distances from points in the input 'graph' to selected lines, subject to constraints. Args: graph (list of int): Represents points on a line. Each element is the distance of a point from the origin. lines_left (int): The remaining number of lines allowed to be used. distance_since_last (int): The distance from the last selected line to the current point being considered. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in 'graph' where lines were placed to achieve the minimum. """ if len(graph) < lines_left: return 1e9, [] # Not enough points for remaining lines if lines_left == 0 and len(graph) == 0: return 0, [] # Base case: no points left # option 1: don't take the line value = (1e9, []) # Initialize with a large value if distance_since_last < 10: # Check if allowed to skip value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) # Recursively solve for rest sub += graph[0] + (distance_since_last-8)**2 # Add cost of current point value = min(value, (sub, how + [len(graph)])) # Update if better return value def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of solve_dp. Args: graph (list of int): Represents points on a line. lines_left (int): The number of lines allowed. distance_since_last (int): Initial distance since the last line. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in 'graph' where lines were placed. """ n = len(graph) dp = [[[ (1e9, []) for _ in range(distance_since_last + n + 1)] for _ in range(lines_left + 1)] for _ in range(n + 1)] # Initialize base cases for i in range(n + 1): for j in range(distance_since_last + n + 1): dp[i][0][j] = (0, []) if i == 0 else (1e9, []) # Iterate through the subproblems for i in range(1, n + 1): for j in range(1, lines_left + 1): for k in range(distance_since_last + n + 1): # Don't take the line dp[i][j][k] = dp[i - 1][j][k + 1] if k < distance_since_last + n else (1e9, []) # Take the line if j > 0: sub_problem = dp[i - 1][j - 1][0] cost = sub_problem[0] + graph[i - 1] + (k - 8) ** 2 if cost < dp[i][j][k][0]: dp[i][j][k] = (cost, sub_problem[1] + [i]) return dp[n][lines_left][distance_since_last] |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function aims to minimize the sum of squared distances from points in the input 'graph' to selected lines, subject to constraints. Args: graph (list of int): Represents points on a line. Each element is the distance of a point from the origin. lines_left (int): The remaining number of lines allowed to be used. distance_since_last (int): The distance from the last selected line to the current point being considered. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in 'graph' where lines were placed to achieve the minimum. """ if len(graph) < lines_left: return 1e9, [] # Not enough points for remaining lines if lines_left == 0 and len(graph) == 0: return 0, [] # Base case: no points left # option 1: don't take the line value = (1e9, []) # Initialize with a large value if distance_since_last < 10: # Check if allowed to skip value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) # Recursively solve for rest sub += graph[0] + (distance_since_last-8)**2 # Add cost of current point value = min(value, (sub, how + [len(graph)])) # Update if better return value def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of solve_dp. Args: graph (list of int): Represents points on a line. lines_left (int): The number of lines allowed. distance_since_last (int): Initial distance since the last line. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in 'graph' where lines were placed. """ n = len(graph) dp = [[[ (1e9, []) for _ in range(distance_since_last + n + 1)] for _ in range(lines_left + 1)] for _ in range(n + 1)] # Initialize base cases for i in range(n + 1): for j in range(distance_since_last + n + 1): dp[i][0][j] = (0, []) if i == 0 else (1e9, []) # Iterate through the subproblems for i in range(1, n + 1): for j in range(1, lines_left + 1): for k in range(distance_since_last + n + 1): # Don't take the line dp[i][j][k] = dp[i - 1][j][k + 1] if k < distance_since_last + n else (1e9, []) # Take the line if j > 0: sub_problem = dp[i - 1][j - 1][0] cost = sub_problem[0] + graph[i - 1] + (k - 8) ** 2 if cost < dp[i][j][k][0]: dp[i][j][k] = (cost, sub_problem[1] + [i]) return dp[n][lines_left][distance_since_last] |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function aims to minimize the sum of squared distances from points in the input 'graph' to selected lines, subject to constraints. Args: graph (list of int): Represents points on a line. Each element is the distance of a point from the origin. lines_left (int): The remaining number of lines allowed to be used. distance_since_last (int): The distance from the last selected line to the current point being considered. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in 'graph' where lines were placed to achieve the minimum. """ if len(graph) < lines_left: return 1e9, [] # Not enough points for remaining lines if lines_left == 0 and len(graph) == 0: return 0, [] # Base case: no points left # option 1: don't take the line value = (1e9, []) # Initialize with a large value if distance_since_last < 10: # Check if allowed to skip value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) # Recursively solve for rest sub += graph[0] + (distance_since_last-8)**2 # Add cost of current point value = min(value, (sub, how + [len(graph)])) # Update if better return value def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of solve_dp. Args: graph (list of int): Represents points on a line. lines_left (int): The number of lines allowed. distance_since_last (int): Initial distance since the last line. Returns: tuple: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in 'graph' where lines were placed. """ n = len(graph) dp = [[[ (1e9, []) for _ in range(distance_since_last + n + 1)] for _ in range(lines_left + 1)] for _ in range(n + 1)] # Initialize base cases for i in range(n + 1): for j in range(distance_since_last + n + 1): dp[i][0][j] = (0, []) if i == 0 else (1e9, []) # Iterate through the subproblems for i in range(1, n + 1): for j in range(1, lines_left + 1): for k in range(distance_since_last + n + 1): # Don't take the line dp[i][j][k] = dp[i - 1][j][k + 1] if k < distance_since_last + n else (1e9, []) # Take the line if j > 0: sub_problem = dp[i - 1][j - 1][0] cost = sub_problem[0] + graph[i - 1] + (k - 8) ** 2 if cost < dp[i][j][k][0]: dp[i][j][k] = (cost, sub_problem[1] + [i]) return dp[n][lines_left][distance_since_last] answer = 0 import random mylist = list(range(100)) random.shuffle(mylist) from functools import lru_cache @lru_cache(maxsize=None) def my_solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, my_solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = my_solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value answer = solve_iterative(tuple(mylist), len(mylist)//8, 4) expected = my_solve_dp(tuple(mylist), len(mylist)//8, 4) assert answer == expected, f'Wrong answer; got {answer} instead of {expected}' print('All tests passed') |
Traceback (most recent call last):
File "/usr/src/app/main.py", line 110, in <module>
assert answer == expected, f'Wrong answer; got {answer} instead of {expected}'
AssertionError: Wrong answer; got (159, [1, 8, 14, 23, 33, 42, 51, 61, 67, 76, 86, 96]) instead of (170, [5, 11, 21, 25, 34, 40, 50, 59, 68, 78, 87, 97])
Testing if the previous output contains the string All tests passed
: False
Resulting in output: True
Explain what this code does. Then, convert this recursive function to an iterative one, making explicit the cubic work that's being done. The functions should return exactly the same output but the iterative one should be faster. Call your function `solve_iterative` and match the type signature of the original function. @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value
Explain what this code does. Then, convert this recursive function to an iterative one, making explicit the cubic work that's being done. The functions should return exactly the same output but the iterative one should be faster. Call your function `solve_iterative` and match the type signature of the original function. @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function solves a dynamic programming problem where the goal is to minimize the cost of selecting a subset of elements from a 'graph' while adhering to certain constraints. Args: graph (list): A list of integers representing the elements to choose from. lines_left (int): The remaining number of elements allowed to be selected. distance_since_last (int): The distance (in index positions) from the last selected element. Returns: tuple: A tuple containing the minimum cost and the indices of the selected elements. """ if len(graph) < lines_left: return 1e9, [] # Base case: Not enough elements left to satisfy 'lines_left' if lines_left == 0 and len(graph) == 0: return 0, [] # Base case: All elements processed, and constraints met # Option 1: Don't take the current element value = (1e9, []) # Initialize with a very high cost if distance_since_last < 10: # Check if allowed to skip based on distance constraint value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # Option 2: Take the current element (if allowed) if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) # Recursively explore taking the element sub += graph[0] + (distance_since_last-8)**2 # Calculate cost with the current element value = min(value, (sub, how + [len(graph)])) # Update 'value' if the new cost is lower return value # Return the minimum cost and corresponding element selections def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of the `solve_dp` function using dynamic programming. Args: graph (list): A list of integers representing the elements to choose from. lines_left (int): The remaining number of elements allowed to be selected. distance_since_last (int): The distance (in index positions) from the last selected element. Returns: tuple: A tuple containing the minimum cost and the indices of the selected elements. """ n = len(graph) dp = [[[ (1e9, []) for _ in range(11)] for _ in range(lines_left + 1)] for _ in range(n+1)] # Initialize base cases for i in range(n+1): for d in range(11): dp[i][0][d] = (0, []) # Fill the DP table iteratively for i in range(1, n+1): for j in range(1, min(i+1, lines_left+1)): for d in range(1, 11): # Option 1: Don't take the line dp[i][j][d] = dp[i-1][j][d-1] # Option 2: Take the line if j > 0: sub, how = dp[i-1][j-1][0] sub += graph[i-1] + (d-9)**2 dp[i][j][0] = min(dp[i][j][0], (sub, how + [i])) return dp[n][lines_left][distance_since_last] |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function solves a dynamic programming problem where the goal is to minimize the cost of selecting a subset of elements from a 'graph' while adhering to certain constraints. Args: graph (list): A list of integers representing the elements to choose from. lines_left (int): The remaining number of elements allowed to be selected. distance_since_last (int): The distance (in index positions) from the last selected element. Returns: tuple: A tuple containing the minimum cost and the indices of the selected elements. """ if len(graph) < lines_left: return 1e9, [] # Base case: Not enough elements left to satisfy 'lines_left' if lines_left == 0 and len(graph) == 0: return 0, [] # Base case: All elements processed, and constraints met # Option 1: Don't take the current element value = (1e9, []) # Initialize with a very high cost if distance_since_last < 10: # Check if allowed to skip based on distance constraint value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # Option 2: Take the current element (if allowed) if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) # Recursively explore taking the element sub += graph[0] + (distance_since_last-8)**2 # Calculate cost with the current element value = min(value, (sub, how + [len(graph)])) # Update 'value' if the new cost is lower return value # Return the minimum cost and corresponding element selections def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of the `solve_dp` function using dynamic programming. Args: graph (list): A list of integers representing the elements to choose from. lines_left (int): The remaining number of elements allowed to be selected. distance_since_last (int): The distance (in index positions) from the last selected element. Returns: tuple: A tuple containing the minimum cost and the indices of the selected elements. """ n = len(graph) dp = [[[ (1e9, []) for _ in range(11)] for _ in range(lines_left + 1)] for _ in range(n+1)] # Initialize base cases for i in range(n+1): for d in range(11): dp[i][0][d] = (0, []) # Fill the DP table iteratively for i in range(1, n+1): for j in range(1, min(i+1, lines_left+1)): for d in range(1, 11): # Option 1: Don't take the line dp[i][j][d] = dp[i-1][j][d-1] # Option 2: Take the line if j > 0: sub, how = dp[i-1][j-1][0] sub += graph[i-1] + (d-9)**2 dp[i][j][0] = min(dp[i][j][0], (sub, how + [i])) return dp[n][lines_left][distance_since_last] |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function solves a dynamic programming problem where the goal is to minimize the cost of selecting a subset of elements from a 'graph' while adhering to certain constraints. Args: graph (list): A list of integers representing the elements to choose from. lines_left (int): The remaining number of elements allowed to be selected. distance_since_last (int): The distance (in index positions) from the last selected element. Returns: tuple: A tuple containing the minimum cost and the indices of the selected elements. """ if len(graph) < lines_left: return 1e9, [] # Base case: Not enough elements left to satisfy 'lines_left' if lines_left == 0 and len(graph) == 0: return 0, [] # Base case: All elements processed, and constraints met # Option 1: Don't take the current element value = (1e9, []) # Initialize with a very high cost if distance_since_last < 10: # Check if allowed to skip based on distance constraint value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # Option 2: Take the current element (if allowed) if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) # Recursively explore taking the element sub += graph[0] + (distance_since_last-8)**2 # Calculate cost with the current element value = min(value, (sub, how + [len(graph)])) # Update 'value' if the new cost is lower return value # Return the minimum cost and corresponding element selections def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of the `solve_dp` function using dynamic programming. Args: graph (list): A list of integers representing the elements to choose from. lines_left (int): The remaining number of elements allowed to be selected. distance_since_last (int): The distance (in index positions) from the last selected element. Returns: tuple: A tuple containing the minimum cost and the indices of the selected elements. """ n = len(graph) dp = [[[ (1e9, []) for _ in range(11)] for _ in range(lines_left + 1)] for _ in range(n+1)] # Initialize base cases for i in range(n+1): for d in range(11): dp[i][0][d] = (0, []) # Fill the DP table iteratively for i in range(1, n+1): for j in range(1, min(i+1, lines_left+1)): for d in range(1, 11): # Option 1: Don't take the line dp[i][j][d] = dp[i-1][j][d-1] # Option 2: Take the line if j > 0: sub, how = dp[i-1][j-1][0] sub += graph[i-1] + (d-9)**2 dp[i][j][0] = min(dp[i][j][0], (sub, how + [i])) return dp[n][lines_left][distance_since_last] answer = 0 import random mylist = list(range(100)) random.shuffle(mylist) from functools import lru_cache @lru_cache(maxsize=None) def my_solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, my_solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = my_solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value answer = solve_iterative(tuple(mylist), len(mylist)//8, 4) expected = my_solve_dp(tuple(mylist), len(mylist)//8, 4) assert answer == expected, f'Wrong answer; got {answer} instead of {expected}' print('All tests passed') |
Traceback (most recent call last):
File "/usr/src/app/main.py", line 101, in <module>
assert answer == expected, f'Wrong answer; got {answer} instead of {expected}'
AssertionError: Wrong answer; got (487, [85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96]) instead of (174, [7, 17, 26, 34, 45, 51, 57, 65, 75, 80, 87, 96])
Testing if the previous output contains the string All tests passed
: False
Resulting in output: True
Explain what this code does. Then, convert this recursive function to an iterative one, making explicit the cubic work that's being done. The functions should return exactly the same output but the iterative one should be faster. Call your function `solve_iterative` and match the type signature of the original function. @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value
Explain what this code does. Then, convert this recursive function to an iterative one, making explicit the cubic work that's being done. The functions should return exactly the same output but the iterative one should be faster. Call your function `solve_iterative` and match the type signature of the original function. @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function aims to minimize the sum of squared distances from points in a graph to selected "lines". It uses dynamic programming to explore different combinations of lines and their placements. Args: graph: A list of integers representing points on a line. lines_left: The number of lines allowed to be placed. distance_since_last: The distance from the previous line placement. Returns: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in the graph where lines were placed to achieve that minimum. """ if len(graph) < lines_left: return 1e9, [] # Not enough points for remaining lines if lines_left == 0 and len(graph) == 0: return 0, [] # Base case: no lines, no points # Option 1: Don't place a line at the current position value = (1e9, []) # Initialize with a very large value if distance_since_last < 10: # Only consider if distance constraint is met value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # Option 2: Place a line at the current position if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) # Recursively solve for rest of the graph sub += graph[0] + (distance_since_last-8)**2 # Add cost of placing line here value = min(value, (sub, how + [len(graph)])) # Update if this placement is better return value def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of solve_dp using bottom-up dynamic programming. Args: graph: A list of integers representing points on a line. lines_left: The number of lines allowed to be placed. distance_since_last: The distance from the previous line placement. Returns: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in the graph where lines were placed to achieve that minimum. """ n = len(graph) dp = [[[ (1e9, []) for _ in range(11)] for _ in range(lines_left + 1)] for _ in range(n + 1)] # Initialize base cases for i in range(n + 1): for d in range(11): dp[i][0][d] = (0, []) # Fill the dp table iteratively for i in range(1, n + 1): for j in range(1, min(i + 1, lines_left + 1)): for d in range(11): # Option 1: Don't take the line dp[i][j][d] = dp[i - 1][j][min(d + 1, 10)] # Option 2: Take the line if d == 0: sub, how = dp[i - 1][j - 1][0] sub += graph[i - 1] + (10 - 8)**2 # Assuming distance_since_last is initially 10 dp[i][j][d] = min(dp[i][j][d], (sub, how + [i])) return dp[n][lines_left][0] |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function aims to minimize the sum of squared distances from points in a graph to selected "lines". It uses dynamic programming to explore different combinations of lines and their placements. Args: graph: A list of integers representing points on a line. lines_left: The number of lines allowed to be placed. distance_since_last: The distance from the previous line placement. Returns: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in the graph where lines were placed to achieve that minimum. """ if len(graph) < lines_left: return 1e9, [] # Not enough points for remaining lines if lines_left == 0 and len(graph) == 0: return 0, [] # Base case: no lines, no points # Option 1: Don't place a line at the current position value = (1e9, []) # Initialize with a very large value if distance_since_last < 10: # Only consider if distance constraint is met value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # Option 2: Place a line at the current position if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) # Recursively solve for rest of the graph sub += graph[0] + (distance_since_last-8)**2 # Add cost of placing line here value = min(value, (sub, how + [len(graph)])) # Update if this placement is better return value def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of solve_dp using bottom-up dynamic programming. Args: graph: A list of integers representing points on a line. lines_left: The number of lines allowed to be placed. distance_since_last: The distance from the previous line placement. Returns: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in the graph where lines were placed to achieve that minimum. """ n = len(graph) dp = [[[ (1e9, []) for _ in range(11)] for _ in range(lines_left + 1)] for _ in range(n + 1)] # Initialize base cases for i in range(n + 1): for d in range(11): dp[i][0][d] = (0, []) # Fill the dp table iteratively for i in range(1, n + 1): for j in range(1, min(i + 1, lines_left + 1)): for d in range(11): # Option 1: Don't take the line dp[i][j][d] = dp[i - 1][j][min(d + 1, 10)] # Option 2: Take the line if d == 0: sub, how = dp[i - 1][j - 1][0] sub += graph[i - 1] + (10 - 8)**2 # Assuming distance_since_last is initially 10 dp[i][j][d] = min(dp[i][j][d], (sub, how + [i])) return dp[n][lines_left][0] |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 | from functools import lru_cache @lru_cache(maxsize=None) def solve_dp(graph, lines_left, distance_since_last): """ This function aims to minimize the sum of squared distances from points in a graph to selected "lines". It uses dynamic programming to explore different combinations of lines and their placements. Args: graph: A list of integers representing points on a line. lines_left: The number of lines allowed to be placed. distance_since_last: The distance from the previous line placement. Returns: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in the graph where lines were placed to achieve that minimum. """ if len(graph) < lines_left: return 1e9, [] # Not enough points for remaining lines if lines_left == 0 and len(graph) == 0: return 0, [] # Base case: no lines, no points # Option 1: Don't place a line at the current position value = (1e9, []) # Initialize with a very large value if distance_since_last < 10: # Only consider if distance constraint is met value = min(value, solve_dp(graph[1:], lines_left, distance_since_last+1)) # Option 2: Place a line at the current position if lines_left > 0: sub, how = solve_dp(graph[1:], lines_left-1, 0) # Recursively solve for rest of the graph sub += graph[0] + (distance_since_last-8)**2 # Add cost of placing line here value = min(value, (sub, how + [len(graph)])) # Update if this placement is better return value def solve_iterative(graph, lines_left, distance_since_last): """ Iterative version of solve_dp using bottom-up dynamic programming. Args: graph: A list of integers representing points on a line. lines_left: The number of lines allowed to be placed. distance_since_last: The distance from the previous line placement. Returns: A tuple containing: - The minimum sum of squared distances achieved. - A list of indices in the graph where lines were placed to achieve that minimum. """ n = len(graph) dp = [[[ (1e9, []) for _ in range(11)] for _ in range(lines_left + 1)] for _ in range(n + 1)] # Initialize base cases for i in range(n + 1): for d in range(11): dp[i][0][d] = (0, []) # Fill the dp table iteratively for i in range(1, n + 1): for j in range(1, min(i + 1, lines_left + 1)): for d in range(11): # Option 1: Don't take the line dp[i][j][d] = dp[i - 1][j][min(d + 1, 10)] # Option 2: Take the line if d == 0: sub, how = dp[i - 1][j - 1][0] sub += graph[i - 1] + (10 - 8)**2 # Assuming distance_since_last is initially 10 dp[i][j][d] = min(dp[i][j][d], (sub, how + [i])) return dp[n][lines_left][0] answer = 0 import random mylist = list(range(100)) random.shuffle(mylist) from functools import lru_cache @lru_cache(maxsize=None) def my_solve_dp(graph, lines_left, distance_since_last): if len(graph) < lines_left: return 1e9, [] if lines_left == 0 and len(graph) == 0: return 0, [] # option 1: don't take the line value = (1e9, []) if distance_since_last < 10: value = min(value, my_solve_dp(graph[1:], lines_left, distance_since_last+1)) # option 2: take the line if lines_left > 0: sub, how = my_solve_dp(graph[1:], lines_left-1, 0) sub += graph[0] + (distance_since_last-8)**2 value = min(value, (sub, how + [len(graph)])) return value answer = solve_iterative(tuple(mylist), len(mylist)//8, 4) expected = my_solve_dp(tuple(mylist), len(mylist)//8, 4) assert answer == expected, f'Wrong answer; got {answer} instead of {expected}' print('All tests passed') |
Traceback (most recent call last):
File "/usr/src/app/main.py", line 107, in <module>
assert answer == expected, f'Wrong answer; got {answer} instead of {expected}'
AssertionError: Wrong answer; got (576, [89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100]) instead of (146, [5, 11, 21, 29, 35, 46, 56, 64, 69, 77, 85, 94])
Testing if the previous output contains the string All tests passed
: False
Resulting in output: True