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
This recursive function `solve_dp` calculates the minimum cost of taking or not taking a line from a graph based on certain conditions. The function takes in a graph (list of integers), the number of lines left to take, and the distance since the last line was taken. It recursively explores two options at each step: either not taking the line or taking the line. It considers the cost of taking the line based on the distance since the last line was taken and the penalty for taking the line too soon. To convert this recursive function into an iterative one, we can use dynamic programming to store and update the results of subproblems. We can iterate through the graph and lines_left to calculate the minimum cost for each subproblem in a bottom-up manner. This will ensure that each subproblem is only calculated once and will reduce the overall computational complexity. Here is the iterative function `solve_iterative`:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | def solve_iterative(graph, lines_left, distance_since_last): dp = [[1e9 for _ in range(len(graph)+1)] for _ in range(lines_left+1)] dp[0][0] = 0 for i in range(1, lines_left+1): for j in range(len(graph)+1): if j < i: continue value = 1e9 if distance_since_last < 10: value = dp[i][j-1] if j > 0: sub = dp[i-1][j-1] + graph[j-1] + (distance_since_last-8)**2 value = min(value, sub) dp[i][j] = value min_cost = min(dp[lines_left]) min_index = dp[lines_left].index(min_cost) return min_cost, dp[lines_left][:min_index] |
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 | def solve_iterative(graph, lines_left, distance_since_last): dp = [[1e9 for _ in range(len(graph)+1)] for _ in range(lines_left+1)] dp[0][0] = 0 for i in range(1, lines_left+1): for j in range(len(graph)+1): if j < i: continue value = 1e9 if distance_since_last < 10: value = dp[i][j-1] if j > 0: sub = dp[i-1][j-1] + graph[j-1] + (distance_since_last-8)**2 value = min(value, sub) dp[i][j] = value min_cost = min(dp[lines_left]) min_index = dp[lines_left].index(min_cost) return min_cost, dp[lines_left][:min_index] |
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 | def solve_iterative(graph, lines_left, distance_since_last): dp = [[1e9 for _ in range(len(graph)+1)] for _ in range(lines_left+1)] dp[0][0] = 0 for i in range(1, lines_left+1): for j in range(len(graph)+1): if j < i: continue value = 1e9 if distance_since_last < 10: value = dp[i][j-1] if j > 0: sub = dp[i-1][j-1] + graph[j-1] + (distance_since_last-8)**2 value = min(value, sub) dp[i][j] = value min_cost = min(dp[lines_left]) min_index = dp[lines_left].index(min_cost) return min_cost, dp[lines_left][:min_index] 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 57, in <module>
assert answer == expected, f'Wrong answer; got {answer} instead of {expected}'
^^^^^^^^^^^^^^^^^^
AssertionError: Wrong answer; got (263, [1000000000.0, 1000000000.0, 1000000000.0, 1000000000.0, 1000000000.0, 1000000000.0, 1000000000.0, 1000000000.0, 1000000000.0, 1000000000.0, 1000000000.0, 1000000000.0, 739, 739, 737, 685, 685, 636, 628, 580, 550, 550, 508, 482, 441, 441, 441, 441, 441, 441, 441, 405, 405, 405, 405, 393, 393, 393, 393, 365, 365, 351, 351, 351, 351, 341, 341, 341, 341, 341, 341, 341, 340, 340, 339, 339, 339, 339, 339, 339, 339, 330, 330, 330, 309, 295, 295, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 284, 279, 278, 278, 273, 273]) instead of (182, [2, 10, 19, 28, 37, 47, 56, 62, 70, 77, 86, 95])
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
This recursive function `solve_dp` is using dynamic programming to solve a problem related to lines in a graph. It calculates the minimum cost of selecting a certain number of lines while considering the distance since the last line taken. To convert this recursive function to an iterative one, we can use a bottom-up approach to simulate the recursive calls iteratively. By doing so, we can avoid the overhead of function calls and improve the performance. Here is the iterative version of the function:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | def solve_iterative(graph, lines_left, distance_since_last): dp = [[1e9, []] * (lines_left + 1) for _ in range(len(graph) + 1)] for i in range(len(graph), -1, -1): for j in range(lines_left + 1): if len(graph) < j: dp[i][j] = 1e9, [] elif j == 0 and i == 0: dp[i][j] = 0, [] else: value = (1e9, []) if distance_since_last < 10: value = min(value, dp[i+1][j], dp[i+1][j], distance_since_last+1) if j > 0: sub, how = dp[i+1][j-1] sub += graph[i] + (distance_since_last-8)**2 value = min(value, (sub, how + [i])) dp[i][j] = value return dp[0][lines_left] |
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 | def solve_iterative(graph, lines_left, distance_since_last): dp = [[1e9, []] * (lines_left + 1) for _ in range(len(graph) + 1)] for i in range(len(graph), -1, -1): for j in range(lines_left + 1): if len(graph) < j: dp[i][j] = 1e9, [] elif j == 0 and i == 0: dp[i][j] = 0, [] else: value = (1e9, []) if distance_since_last < 10: value = min(value, dp[i+1][j], dp[i+1][j], distance_since_last+1) if j > 0: sub, how = dp[i+1][j-1] sub += graph[i] + (distance_since_last-8)**2 value = min(value, (sub, how + [i])) dp[i][j] = value return dp[0][lines_left] |
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 | def solve_iterative(graph, lines_left, distance_since_last): dp = [[1e9, []] * (lines_left + 1) for _ in range(len(graph) + 1)] for i in range(len(graph), -1, -1): for j in range(lines_left + 1): if len(graph) < j: dp[i][j] = 1e9, [] elif j == 0 and i == 0: dp[i][j] = 0, [] else: value = (1e9, []) if distance_since_last < 10: value = min(value, dp[i+1][j], dp[i+1][j], distance_since_last+1) if j > 0: sub, how = dp[i+1][j-1] sub += graph[i] + (distance_since_last-8)**2 value = min(value, (sub, how + [i])) dp[i][j] = value return dp[0][lines_left] 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 54, in <module>
answer = solve_iterative(tuple(mylist), len(mylist)//8, 4)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/src/app/main.py", line 14, in solve_iterative
value = min(value, dp[i+1][j], dp[i+1][j], distance_since_last+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
This recursive function `solve_dp` takes in a graph representing distances between locations, the number of lines left to draw on the graph, and the distance since the last line was drawn. It recursively calculates the minimum cost of drawing lines on the graph based on two options: either not taking the current line or taking the current line. The cost is calculated based on the distance since the last line was drawn, the length of the current line, and the index of the current line in the graph. To convert this recursive function to an iterative one, we can use dynamic programming to store the results of subproblems and build up the solution iteratively. Here is the iterative version of the function:
1 2 3 4 5 6 7 8 9 10 11 12 | def solve_iterative(graph, lines_left, distance_since_last): n = len(graph) dp = [[1e9, []] for _ in range(lines_left + 1)] dp[0] = [0, []] for i in range(1, n + 1): for j in range(min(i, lines_left), 0, -1): # option 1: don't take the line if distance_since_last < 10: dp[j] = min(dp[j], [dp[j-1][0] + graph[i-1] + (distance_since_last-8)**2, dp[j-1][1] + [i]]) return dp[lines_left] |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 | def solve_iterative(graph, lines_left, distance_since_last): n = len(graph) dp = [[1e9, []] for _ in range(lines_left + 1)] dp[0] = [0, []] for i in range(1, n + 1): for j in range(min(i, lines_left), 0, -1): # option 1: don't take the line if distance_since_last < 10: dp[j] = min(dp[j], [dp[j-1][0] + graph[i-1] + (distance_since_last-8)**2, dp[j-1][1] + [i]]) return dp[lines_left] |
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 | def solve_iterative(graph, lines_left, distance_since_last): n = len(graph) dp = [[1e9, []] for _ in range(lines_left + 1)] dp[0] = [0, []] for i in range(1, n + 1): for j in range(min(i, lines_left), 0, -1): # option 1: don't take the line if distance_since_last < 10: dp[j] = min(dp[j], [dp[j-1][0] + graph[i-1] + (distance_since_last-8)**2, dp[j-1][1] + [i]]) return dp[lines_left] 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 47, in <module>
assert answer == expected, f'Wrong answer; got {answer} instead of {expected}'
^^^^^^^^^^^^^^^^^^
AssertionError: Wrong answer; got [258, [5, 6, 12, 16, 27, 32, 43, 48, 60, 73, 78, 79]] instead of (172, [2, 11, 22, 28, 35, 43, 53, 60, 69, 74, 85, 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
This code defines a recursive function `solve_dp` that calculates the minimum cost and path to traverse a graph with a given number of lines left and distance since the last line. The function considers two options at each step: either not taking the current line or taking the current line. It then recursively calculates the cost and path for both options and returns the minimum cost and corresponding path. To convert this recursive function into an iterative one, we can use dynamic programming to store and reuse the results of subproblems. We will create a 3D table to store the results for each combination of `graph`, `lines_left`, and `distance_since_last`. We will then iteratively fill in the table starting from the base cases and building up to the final result. This iterative approach will eliminate the overhead of recursive function calls and improve the performance of the function. Here is the iterative version of the function:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | def solve_iterative(graph, lines_left, distance_since_last): n = len(graph) dp = [[[1e9, []] * 11 for _ in range(lines_left + 1)] for _ in range(n + 1] for i in range(n + 1): dp[i][0][0] = 0 for i in range(n - 1, -1, -1): for j in range(1, lines_left + 1): for k in range(11): value = dp[i + 1][j][k] if k < 10: value = min(value, dp[i + 1][j][k + 1]) if j > 0: sub = dp[i + 1][j - 1][0][0] + graph[i] + (k - 8) ** 2 if sub < value: dp[i][j][k] = sub dp[i][j][k][1] = dp[i + 1][j - 1][0][1] + [i] return dp[0][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 | def solve_iterative(graph, lines_left, distance_since_last): n = len(graph) dp = [[[1e9, []] * 11 for _ in range(lines_left + 1)] for _ in range(n + 1] for i in range(n + 1): dp[i][0][0] = 0 for i in range(n - 1, -1, -1): for j in range(1, lines_left + 1): for k in range(11): value = dp[i + 1][j][k] if k < 10: value = min(value, dp[i + 1][j][k + 1]) if j > 0: sub = dp[i + 1][j - 1][0][0] + graph[i] + (k - 8) ** 2 if sub < value: dp[i][j][k] = sub dp[i][j][k][1] = dp[i + 1][j - 1][0][1] + [i] return dp[0][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 | def solve_iterative(graph, lines_left, distance_since_last): n = len(graph) dp = [[[1e9, []] * 11 for _ in range(lines_left + 1)] for _ in range(n + 1] for i in range(n + 1): dp[i][0][0] = 0 for i in range(n - 1, -1, -1): for j in range(1, lines_left + 1): for k in range(11): value = dp[i + 1][j][k] if k < 10: value = min(value, dp[i + 1][j][k + 1]) if j > 0: sub = dp[i + 1][j - 1][0][0] + graph[i] + (k - 8) ** 2 if sub < value: dp[i][j][k] = sub dp[i][j][k][1] = dp[i + 1][j - 1][0][1] + [i] return dp[0][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') |
File "/usr/src/app/main.py", line 4
dp = [[[1e9, []] * 11 for _ in range(lines_left + 1)] for _ in range(n + 1]
^
SyntaxError: closing parenthesis ']' does not match opening parenthesis '('
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
This recursive function `solve_dp` takes in a graph, the number of lines left to take, and the distance since the last line taken. It calculates the minimum cost and path to take all the lines in the graph under certain conditions. The cost is based on the distance between consecutive lines and the number of lines taken. To convert this recursive function to an iterative one, we can use dynamic programming to store the results of subproblems in a table and build up the solution iteratively. Here is the iterative version of the function:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | def solve_iterative(graph, lines_left, distance_since_last): dp = [[1e9, []] * (lines_left + 1) for _ in range(len(graph) + 1)] for i in range(len(graph), -1, -1): for j in range(lines_left + 1): if i == len(graph) and j == 0: dp[i][j] = 0, [] else: value = (1e9, []) if distance_since_last < 10: value = dp[i + 1][j] if j > 0: sub, how = dp[i + 1][j - 1] sub += graph[i] + (distance_since_last - 8) ** 2 value = min(value, (sub, how + [i])) dp[i][j] = value return dp[0][lines_left] |
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 | def solve_iterative(graph, lines_left, distance_since_last): dp = [[1e9, []] * (lines_left + 1) for _ in range(len(graph) + 1)] for i in range(len(graph), -1, -1): for j in range(lines_left + 1): if i == len(graph) and j == 0: dp[i][j] = 0, [] else: value = (1e9, []) if distance_since_last < 10: value = dp[i + 1][j] if j > 0: sub, how = dp[i + 1][j - 1] sub += graph[i] + (distance_since_last - 8) ** 2 value = min(value, (sub, how + [i])) dp[i][j] = value return dp[0][lines_left] |
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 | def solve_iterative(graph, lines_left, distance_since_last): dp = [[1e9, []] * (lines_left + 1) for _ in range(len(graph) + 1)] for i in range(len(graph), -1, -1): for j in range(lines_left + 1): if i == len(graph) and j == 0: dp[i][j] = 0, [] else: value = (1e9, []) if distance_since_last < 10: value = dp[i + 1][j] if j > 0: sub, how = dp[i + 1][j - 1] sub += graph[i] + (distance_since_last - 8) ** 2 value = min(value, (sub, how + [i])) dp[i][j] = value return dp[0][lines_left] 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 52, in <module>
answer = solve_iterative(tuple(mylist), len(mylist)//8, 4)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/src/app/main.py", line 12, in solve_iterative
value = dp[i + 1][j]
~~^^^^^^^
IndexError: list index out of range
Testing if the previous output contains the string All tests passed
: False
Resulting in output: True