Code golf this function to be a lot shorter. You only get points if it's <300 bytes (not counting whitespace). Keep the function named `count`.
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 | int count() { int ROWS = 8; int COLS = 8; int count = 0; for (int i = 0; i < 1<<16; i++) { long long unsigned int array = ((i & 0xf) << 9) | ((i & 0xf0) << (9 + 8 - 4)) | ((i & 0xf00) << (9 + 8 - 4 + 8 - 4)) | ((i & 0xf000) << (9 + 8 - 4 + 8 - 4 + 8 - 4)); long long unsigned int init = array; long long unsigned int temp = array; for (int i = 1; i < ROWS - 1; i++) { for (int j = 1; j < COLS - 1; j++) { // Calculate bit positions int pos = i * COLS + j; int topPos = (i - 1) * COLS + j; int leftPos = i * COLS + (j - 1); int bottomPos = (i + 1) * COLS + j; int rightPos = i * COLS + (j + 1); // Get the values of the neighbors int cell = (temp >> pos) & 1; int top = (temp >> topPos) & 1; int left = (temp >> leftPos) & 1; int bottom = (temp >> bottomPos) & 1; int right = (temp >> rightPos) & 1; // Sum the values of the neighbors int sum = top + left + bottom + right; // Update the cell if all neighbors are 0 and the cell itself is 1 if (sum == 0 && cell == 1) { array &= ~(1ULL << pos); } } } count += (init == array); } return count; } |
Code golf this function to be a lot shorter. You only get points if it's <300 bytes (not counting whitespace). Keep the function named `count`.
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 | int count() { int ROWS = 8; int COLS = 8; int count = 0; for (int i = 0; i < 1<<16; i++) { long long unsigned int array = ((i & 0xf) << 9) | ((i & 0xf0) << (9 + 8 - 4)) | ((i & 0xf00) << (9 + 8 - 4 + 8 - 4)) | ((i & 0xf000) << (9 + 8 - 4 + 8 - 4 + 8 - 4)); long long unsigned int init = array; long long unsigned int temp = array; for (int i = 1; i < ROWS - 1; i++) { for (int j = 1; j < COLS - 1; j++) { // Calculate bit positions int pos = i * COLS + j; int topPos = (i - 1) * COLS + j; int leftPos = i * COLS + (j - 1); int bottomPos = (i + 1) * COLS + j; int rightPos = i * COLS + (j + 1); // Get the values of the neighbors int cell = (temp >> pos) & 1; int top = (temp >> topPos) & 1; int left = (temp >> leftPos) & 1; int bottom = (temp >> bottomPos) & 1; int right = (temp >> rightPos) & 1; // Sum the values of the neighbors int sum = top + left + bottom + right; // Update the cell if all neighbors are 0 and the cell itself is 1 if (sum == 0 && cell == 1) { array &= ~(1ULL << pos); } } } count += (init == array); } return count; } |
## Breaking Down the Code The provided function `count` iterates through all possible combinations of an 8x8 binary grid. For each combination, it simulates a single step of a cellular automata rule where a cell becomes 'off' (0) if and only if all its neighbors are 'off'. The function then counts how many initial configurations remain unchanged after this single step. ## Optimization Strategies 1. **Eliminate Unnecessary Variables:** We can directly calculate bit positions instead of using separate variables. 2. **Combine Loops:** The nested loops for iterating over the grid can be merged into a single loop. 3. **Bit Manipulation Optimization:** We can streamline the neighbor checking and update logic using bitwise operations. ## Golfed Code (Attempt 1)
1 | int count(){int c=0;for(int i=0;i<65536;i++){long long a=((i&15)<<9)|((i&240)<<5)|((i&3840)<<1)|((i&61440)>>3),t=a;for(int j=1;j<63;j++){int p=j*8;int s=((t>>(p-8))&1)+((t>>(p-1))&1)+((t>>(p+1))&1)+((t>>(p+8))&1);if((s==0)&&(t&(1LL<<p)))a&=~(1LL<<p);}c+=(a==t);}return c;} |
1 | int count(){int c=0;for(int i=0;i<65536;++i){long long a=((i&15)<<9)|((i&240)<<5)|((i&3840)<<1)|((i&61440)>>3),t=a;for(int j=1;j<63;++j){long long p=j*8,s=((t>>(p-8))&1)+((t>>(p-1))&1)+((t>>(p+1))&1)+((t>>(p+8))&1);a=s||!(t&(1LL<<p))?a:a&~(1LL<<p);}c+=(a==t);}return c;} |
I extracted the following code from that output:
1 | int count(){int c=0;for(int i=0;i<65536;++i){long long a=((i&15)<<9)|((i&240)<<5)|((i&3840)<<1)|((i&61440)>>3),t=a;for(int j=1;j<63;++j){long long p=j*8,s=((t>>(p-8))&1)+((t>>(p-1))&1)+((t>>(p+1))&1)+((t>>(p+8))&1);a=s||!(t&(1LL<<p))?a:a&~(1LL<<p);}c+=(a==t);}return c;} |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | int count(){int c=0;for(int i=0;i<65536;++i){long long a=((i&15)<<9)|((i&240)<<5)|((i&3840)<<1)|((i&61440)>>3),t=a;for(int j=1;j<63;++j){long long p=j*8,s=((t>>(p-8))&1)+((t>>(p-1))&1)+((t>>(p+1))&1)+((t>>(p+8))&1);a=s||!(t&(1LL<<p))?a:a&~(1LL<<p);}c+=(a==t);}return c;} #include<stdio.h> #include<stdlib.h> int main() { int answer = count(); int expected = 27488; if (answer != expected) { printf("Wrong answer; got %d instead of %d.\n", answer, expected); exit(1); } printf("All tests passed\n"); } |
Wrong answer; got 65536 instead of 27488.
Testing if the previous output contains the string All tests passed
: False
Resulting in output: True
Code golf this function to be a lot shorter. You only get points if it's <300 bytes (not counting whitespace). Keep the function named `count`.
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 | int count() { int ROWS = 8; int COLS = 8; int count = 0; for (int i = 0; i < 1<<16; i++) { long long unsigned int array = ((i & 0xf) << 9) | ((i & 0xf0) << (9 + 8 - 4)) | ((i & 0xf00) << (9 + 8 - 4 + 8 - 4)) | ((i & 0xf000) << (9 + 8 - 4 + 8 - 4 + 8 - 4)); long long unsigned int init = array; long long unsigned int temp = array; for (int i = 1; i < ROWS - 1; i++) { for (int j = 1; j < COLS - 1; j++) { // Calculate bit positions int pos = i * COLS + j; int topPos = (i - 1) * COLS + j; int leftPos = i * COLS + (j - 1); int bottomPos = (i + 1) * COLS + j; int rightPos = i * COLS + (j + 1); // Get the values of the neighbors int cell = (temp >> pos) & 1; int top = (temp >> topPos) & 1; int left = (temp >> leftPos) & 1; int bottom = (temp >> bottomPos) & 1; int right = (temp >> rightPos) & 1; // Sum the values of the neighbors int sum = top + left + bottom + right; // Update the cell if all neighbors are 0 and the cell itself is 1 if (sum == 0 && cell == 1) { array &= ~(1ULL << pos); } } } count += (init == array); } return count; } |
Code golf this function to be a lot shorter. You only get points if it's <300 bytes (not counting whitespace). Keep the function named `count`.
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 | int count() { int ROWS = 8; int COLS = 8; int count = 0; for (int i = 0; i < 1<<16; i++) { long long unsigned int array = ((i & 0xf) << 9) | ((i & 0xf0) << (9 + 8 - 4)) | ((i & 0xf00) << (9 + 8 - 4 + 8 - 4)) | ((i & 0xf000) << (9 + 8 - 4 + 8 - 4 + 8 - 4)); long long unsigned int init = array; long long unsigned int temp = array; for (int i = 1; i < ROWS - 1; i++) { for (int j = 1; j < COLS - 1; j++) { // Calculate bit positions int pos = i * COLS + j; int topPos = (i - 1) * COLS + j; int leftPos = i * COLS + (j - 1); int bottomPos = (i + 1) * COLS + j; int rightPos = i * COLS + (j + 1); // Get the values of the neighbors int cell = (temp >> pos) & 1; int top = (temp >> topPos) & 1; int left = (temp >> leftPos) & 1; int bottom = (temp >> bottomPos) & 1; int right = (temp >> rightPos) & 1; // Sum the values of the neighbors int sum = top + left + bottom + right; // Update the cell if all neighbors are 0 and the cell itself is 1 if (sum == 0 && cell == 1) { array &= ~(1ULL << pos); } } } count += (init == array); } return count; } |
## Breakdown and Golfing of the `count` Function ### 1. Explanation The `count` function iterates through all possible arrangements of 16 bits representing an 8x8 grid. For each arrangement, it simulates one step of a cellular automata rule where a cell "dies" (becomes 0) if and only if all its neighbors are 0. The function then counts how many initial arrangements remain unchanged after this single step. ### 2. Optimization Strategies * **Eliminate unnecessary variables:** Many variables can be substituted directly into calculations. * **Bitwise operations:** Utilize bitwise operations for compact conditionals and updates. * **Loop unrolling:** Since the grid size is small, unrolling the inner loop can eliminate loop overhead. * **Combine expressions:** Combine multiple statements into single expressions where possible. ### 3. Golfed Function (Attempt 1)
1 | int count(){int c=0;for(int i=0;i<65536;i++){long long a=((i&15)<<9)|((i&240)<<5)|((i&3840)<<1)|((i&61440)>>3),t=a;for(int j=1;j<7;j++){for(int k=1;k<7;k++){int p=j*8+k,s=((t>>(p-8))&1)+((t>>(p-1))&1)+((t>>(p+1))&1)+((t>>(p+8))&1);a&=~(((s|t>>p)&1)<<p);}}c+=(a==t);}return c;} |
1 | int count(){int c=0;for(int i=0;i<65536;++i){long long a=((i&15)<<9)|((i&240)<<5)|((i&3840)<<1)|((i&61440)>>3),t=a;for(int j=8;j<56;j++){a&=~((((t>>(j-8))&1)+((t>>(j-1))&1)+((t>>(j+1))&1)+((t>>(j+8))&1)|t>>j)&1)<<j;}c+=(a==t);}return c;} |
I extracted the following code from that output:
1 2 3 | #include <stdint.h> int count(){int c=0;for(int i=0;i<65536;++i){long long a=((i&15)<<9)|((i&240)<<5)|((i&3840)<<1)|((i&61440)>>3),t=a;for(int j=8;j<56;j++){a&=~((((t>>(j-8))&1)+((t>>(j-1))&1)+((t>>(j+1))&1)+((t>>(j+8))&1)|t>>j)&1)<<j;}c+=(a==t);}return c;} |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | #include <stdint.h> int count(){int c=0;for(int i=0;i<65536;++i){long long a=((i&15)<<9)|((i&240)<<5)|((i&3840)<<1)|((i&61440)>>3),t=a;for(int j=8;j<56;j++){a&=~((((t>>(j-8))&1)+((t>>(j-1))&1)+((t>>(j+1))&1)+((t>>(j+8))&1)|t>>j)&1)<<j;}c+=(a==t);}return c;} #include<stdio.h> #include<stdlib.h> int main() { int answer = count(); int expected = 27488; if (answer != expected) { printf("Wrong answer; got %d instead of %d.\n", answer, expected); exit(1); } printf("All tests passed\n"); } |
Wrong answer; got 1 instead of 27488.
Testing if the previous output contains the string All tests passed
: False
Resulting in output: True
Code golf this function to be a lot shorter. You only get points if it's <300 bytes (not counting whitespace). Keep the function named `count`.
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 | int count() { int ROWS = 8; int COLS = 8; int count = 0; for (int i = 0; i < 1<<16; i++) { long long unsigned int array = ((i & 0xf) << 9) | ((i & 0xf0) << (9 + 8 - 4)) | ((i & 0xf00) << (9 + 8 - 4 + 8 - 4)) | ((i & 0xf000) << (9 + 8 - 4 + 8 - 4 + 8 - 4)); long long unsigned int init = array; long long unsigned int temp = array; for (int i = 1; i < ROWS - 1; i++) { for (int j = 1; j < COLS - 1; j++) { // Calculate bit positions int pos = i * COLS + j; int topPos = (i - 1) * COLS + j; int leftPos = i * COLS + (j - 1); int bottomPos = (i + 1) * COLS + j; int rightPos = i * COLS + (j + 1); // Get the values of the neighbors int cell = (temp >> pos) & 1; int top = (temp >> topPos) & 1; int left = (temp >> leftPos) & 1; int bottom = (temp >> bottomPos) & 1; int right = (temp >> rightPos) & 1; // Sum the values of the neighbors int sum = top + left + bottom + right; // Update the cell if all neighbors are 0 and the cell itself is 1 if (sum == 0 && cell == 1) { array &= ~(1ULL << pos); } } } count += (init == array); } return count; } |
Code golf this function to be a lot shorter. You only get points if it's <300 bytes (not counting whitespace). Keep the function named `count`.
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 | int count() { int ROWS = 8; int COLS = 8; int count = 0; for (int i = 0; i < 1<<16; i++) { long long unsigned int array = ((i & 0xf) << 9) | ((i & 0xf0) << (9 + 8 - 4)) | ((i & 0xf00) << (9 + 8 - 4 + 8 - 4)) | ((i & 0xf000) << (9 + 8 - 4 + 8 - 4 + 8 - 4)); long long unsigned int init = array; long long unsigned int temp = array; for (int i = 1; i < ROWS - 1; i++) { for (int j = 1; j < COLS - 1; j++) { // Calculate bit positions int pos = i * COLS + j; int topPos = (i - 1) * COLS + j; int leftPos = i * COLS + (j - 1); int bottomPos = (i + 1) * COLS + j; int rightPos = i * COLS + (j + 1); // Get the values of the neighbors int cell = (temp >> pos) & 1; int top = (temp >> topPos) & 1; int left = (temp >> leftPos) & 1; int bottom = (temp >> bottomPos) & 1; int right = (temp >> rightPos) & 1; // Sum the values of the neighbors int sum = top + left + bottom + right; // Update the cell if all neighbors are 0 and the cell itself is 1 if (sum == 0 && cell == 1) { array &= ~(1ULL << pos); } } } count += (init == array); } return count; } |
## Understanding the Code This function, `count`, iterates through all possible combinations of 16 bits arranged in an 8x8 grid. For each combination, it simulates a single step of a cellular automaton rule similar to Conway's Game of Life, but with a specific constraint: a cell turns off (becomes 0) if and only if it's currently on (1) and all its neighbors are off (0). The function then counts how many of these initial 16-bit combinations remain unchanged after this single step of the automaton. ## Optimization Strategies 1. **Bit Manipulation:** The core logic heavily relies on bitwise operations. We can exploit this further to eliminate redundant calculations and loops. 2. **Eliminate Redundant Variables:** Variables like `ROWS`, `COLS`, `topPos`, `leftPos`, etc., can be replaced with their constant values directly within the calculations. 3. **Combine Conditions:** The conditions for updating a cell can be combined into a single bitwise expression. ## Golfed Code (Attempt 1)
1 2 3 4 5 6 7 8 9 10 11 12 13 | int count(){ int c=0; for(int i=0;i<1<<16;i++){ long long a=((i&0xf)<<9)|((i&0xf0)<<5)|((i&0xf00)<<1)|((i>>12)&0xf); long long t=a; for(int j=1;j<7;j++) for(int k=1;k<7;k++) if((t>>(j*8+k))&1&&!((t>>(j*8+k-1))&1|(t>>(j*8+k+1))&1|(t>>((j-1)*8+k))&1|(t>>((j+1)*8+k))&1)) a&=~(1ULL<<(j*8+k)); c+=(a==t); } return c; } |
1 2 3 4 5 6 7 8 9 10 11 | int count(){ int c=0; for(int i=0;i<1<<16;i++){ long long a=((i&0xf)<<9)|((i&0xf0)<<5)|((i&0xf00)<<1)|((i>>12)&0xf),t=a; for(int j=8;j<56;j++) if((a>>j)&1&&!((a>>(j-1)|a>>(j+1)|a>>(j-8)|a>>(j+8))&0x1010101)) t&=~(1ULL<<j); c+=(a==t); } return c; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 | int count(){ int c=0; for(int i=0;i<1<<16;i++){ long long a=((i&0xf)<<9)|((i&0xf0)<<5)|((i&0xf00)<<1)|((i>>12)&0xf),t=a; for(int j=8;j<56;j++) if((a>>j)&1&&!((a>>(j-1)|a>>(j+1)|a>>(j-8)|a>>(j+8))&0x1010101)) t&=~(1ULL<<j); c+=(a==t); } return c; } |
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 | int count(){ int c=0; for(int i=0;i<1<<16;i++){ long long a=((i&0xf)<<9)|((i&0xf0)<<5)|((i&0xf00)<<1)|((i>>12)&0xf),t=a; for(int j=8;j<56;j++) if((a>>j)&1&&!((a>>(j-1)|a>>(j+1)|a>>(j-8)|a>>(j+8))&0x1010101)) t&=~(1ULL<<j); c+=(a==t); } return c; } #include<stdio.h> #include<stdlib.h> int main() { int answer = count(); int expected = 27488; if (answer != expected) { printf("Wrong answer; got %d instead of %d.\n", answer, expected); exit(1); } printf("All tests passed\n"); } |
Wrong answer; got 65536 instead of 27488.
Testing if the previous output contains the string All tests passed
: False
Resulting in output: True
Code golf this function to be a lot shorter. You only get points if it's <300 bytes (not counting whitespace). Keep the function named `count`.
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 | int count() { int ROWS = 8; int COLS = 8; int count = 0; for (int i = 0; i < 1<<16; i++) { long long unsigned int array = ((i & 0xf) << 9) | ((i & 0xf0) << (9 + 8 - 4)) | ((i & 0xf00) << (9 + 8 - 4 + 8 - 4)) | ((i & 0xf000) << (9 + 8 - 4 + 8 - 4 + 8 - 4)); long long unsigned int init = array; long long unsigned int temp = array; for (int i = 1; i < ROWS - 1; i++) { for (int j = 1; j < COLS - 1; j++) { // Calculate bit positions int pos = i * COLS + j; int topPos = (i - 1) * COLS + j; int leftPos = i * COLS + (j - 1); int bottomPos = (i + 1) * COLS + j; int rightPos = i * COLS + (j + 1); // Get the values of the neighbors int cell = (temp >> pos) & 1; int top = (temp >> topPos) & 1; int left = (temp >> leftPos) & 1; int bottom = (temp >> bottomPos) & 1; int right = (temp >> rightPos) & 1; // Sum the values of the neighbors int sum = top + left + bottom + right; // Update the cell if all neighbors are 0 and the cell itself is 1 if (sum == 0 && cell == 1) { array &= ~(1ULL << pos); } } } count += (init == array); } return count; } |
Code golf this function to be a lot shorter. You only get points if it's <300 bytes (not counting whitespace). Keep the function named `count`.
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 | int count() { int ROWS = 8; int COLS = 8; int count = 0; for (int i = 0; i < 1<<16; i++) { long long unsigned int array = ((i & 0xf) << 9) | ((i & 0xf0) << (9 + 8 - 4)) | ((i & 0xf00) << (9 + 8 - 4 + 8 - 4)) | ((i & 0xf000) << (9 + 8 - 4 + 8 - 4 + 8 - 4)); long long unsigned int init = array; long long unsigned int temp = array; for (int i = 1; i < ROWS - 1; i++) { for (int j = 1; j < COLS - 1; j++) { // Calculate bit positions int pos = i * COLS + j; int topPos = (i - 1) * COLS + j; int leftPos = i * COLS + (j - 1); int bottomPos = (i + 1) * COLS + j; int rightPos = i * COLS + (j + 1); // Get the values of the neighbors int cell = (temp >> pos) & 1; int top = (temp >> topPos) & 1; int left = (temp >> leftPos) & 1; int bottom = (temp >> bottomPos) & 1; int right = (temp >> rightPos) & 1; // Sum the values of the neighbors int sum = top + left + bottom + right; // Update the cell if all neighbors are 0 and the cell itself is 1 if (sum == 0 && cell == 1) { array &= ~(1ULL << pos); } } } count += (init == array); } return count; } |
## Understanding the Code This function, `count`, appears to be iterating through all possible combinations of a single 8x8 binary grid. For each grid configuration, it applies a specific rule that resembles a simplified cellular automata step. Let's break it down: 1. **Initialization:** - `ROWS` and `COLS` define the grid dimensions (8x8). - `count`: This variable likely keeps track of something across all grid configurations. - The outer loop (`for (int i...`) iterates through all 2^16 (65,536) possible values of `i`. - Inside this loop, `i` is used to generate a 64-bit `array` representing the 8x8 grid. Each bit in `array` corresponds to a cell in the grid. The code extracts bits from `i` and places them into specific positions in `array` to generate the grid pattern. - `init`: Stores a copy of the initial grid configuration. 2. **Grid Transformation:** - The nested loops (`for (int i...` and `for (int j...`) iterate over each cell within the 8x8 grid. - For each cell at position (i, j), the code calculates the indices of its top, left, bottom, and right neighbors within the 1D `array`. - It extracts the values (0 or 1) of the cell and its neighbors from `temp` (which is a copy of `array`). - It calculates the `sum` of the neighbor values. - The crucial rule: If the `sum` of neighbors is 0 (all neighbors are off) and the cell itself is 1 (on), the cell is turned off in the `array` using a bitwise AND operation (`array &= ~(1ULL << pos);`). 3. **Counting:** - After applying the transformation to the entire grid, the code compares the initial grid (`init`) with the transformed grid (`array`). If they are identical (meaning no cells were changed by the transformation), the `count` is incremented. 4. **Return:** - Finally, the function returns the `count`. ## Golfing Strategies Based on the understanding above, here's how we can shorten the code: 1. **Eliminate Unnecessary Variables:** We can eliminate `ROWS`, `COLS`, `topPos`, `leftPos`, `bottomPos`, and `rightPos` by directly calculating the neighbor indices within the loop conditions and bitwise operations. 2. **Combine Loops:** The nested loops for grid iteration can be merged into a single loop iterating from 1 to 63 (excluding the border cells). 3. **Bit Manipulation Tricks:** We can leverage bitwise operations more effectively to check neighbor values and update the grid without explicitly calculating indices. ## Golfed Code (Final Answer)
1 | int count(){int c=0;for(int i=0;i<65536;i++){long long a=((i&15)<<9)|((i&240)<<5)|((i&3840)<<1)|((i&61440)>>3),t=a;for(int j=1;j<63;j++)if((j%8)&&(j%8!=7)&&(j>8)&&(j<56)&&((t>>j)&1)&&!((t>>(j-9))|(t>>(j-1))|(t>>(j+1))|(t>>(j+9))))a&=~(1ULL<<j);c+=(a==t);}return c;} |
I extracted the following code from that output:
1 | int count(){int c=0;for(int i=0;i<65536;i++){long long a=((i&15)<<9)|((i&240)<<5)|((i&3840)<<1)|((i&61440)>>3),t=a;for(int j=1;j<63;j++)if((j%8)&&(j%8!=7)&&(j>8)&&(j<56)&&((t>>j)&1)&&!((t>>(j-9))|(t>>(j-1))|(t>>(j+1))|(t>>(j+9))))a&=~(1ULL<<j);c+=(a==t);}return c;} |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | int count(){int c=0;for(int i=0;i<65536;i++){long long a=((i&15)<<9)|((i&240)<<5)|((i&3840)<<1)|((i&61440)>>3),t=a;for(int j=1;j<63;j++)if((j%8)&&(j%8!=7)&&(j>8)&&(j<56)&&((t>>j)&1)&&!((t>>(j-9))|(t>>(j-1))|(t>>(j+1))|(t>>(j+9))))a&=~(1ULL<<j);c+=(a==t);}return c;} #include<stdio.h> #include<stdlib.h> int main() { int answer = count(); int expected = 27488; if (answer != expected) { printf("Wrong answer; got %d instead of %d.\n", answer, expected); exit(1); } printf("All tests passed\n"); } |
Wrong answer; got 65536 instead of 27488.
Testing if the previous output contains the string All tests passed
: False
Resulting in output: True
Code golf this function to be a lot shorter. You only get points if it's <300 bytes (not counting whitespace). Keep the function named `count`.
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 | int count() { int ROWS = 8; int COLS = 8; int count = 0; for (int i = 0; i < 1<<16; i++) { long long unsigned int array = ((i & 0xf) << 9) | ((i & 0xf0) << (9 + 8 - 4)) | ((i & 0xf00) << (9 + 8 - 4 + 8 - 4)) | ((i & 0xf000) << (9 + 8 - 4 + 8 - 4 + 8 - 4)); long long unsigned int init = array; long long unsigned int temp = array; for (int i = 1; i < ROWS - 1; i++) { for (int j = 1; j < COLS - 1; j++) { // Calculate bit positions int pos = i * COLS + j; int topPos = (i - 1) * COLS + j; int leftPos = i * COLS + (j - 1); int bottomPos = (i + 1) * COLS + j; int rightPos = i * COLS + (j + 1); // Get the values of the neighbors int cell = (temp >> pos) & 1; int top = (temp >> topPos) & 1; int left = (temp >> leftPos) & 1; int bottom = (temp >> bottomPos) & 1; int right = (temp >> rightPos) & 1; // Sum the values of the neighbors int sum = top + left + bottom + right; // Update the cell if all neighbors are 0 and the cell itself is 1 if (sum == 0 && cell == 1) { array &= ~(1ULL << pos); } } } count += (init == array); } return count; } |
Code golf this function to be a lot shorter. You only get points if it's <300 bytes (not counting whitespace). Keep the function named `count`.
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 | int count() { int ROWS = 8; int COLS = 8; int count = 0; for (int i = 0; i < 1<<16; i++) { long long unsigned int array = ((i & 0xf) << 9) | ((i & 0xf0) << (9 + 8 - 4)) | ((i & 0xf00) << (9 + 8 - 4 + 8 - 4)) | ((i & 0xf000) << (9 + 8 - 4 + 8 - 4 + 8 - 4)); long long unsigned int init = array; long long unsigned int temp = array; for (int i = 1; i < ROWS - 1; i++) { for (int j = 1; j < COLS - 1; j++) { // Calculate bit positions int pos = i * COLS + j; int topPos = (i - 1) * COLS + j; int leftPos = i * COLS + (j - 1); int bottomPos = (i + 1) * COLS + j; int rightPos = i * COLS + (j + 1); // Get the values of the neighbors int cell = (temp >> pos) & 1; int top = (temp >> topPos) & 1; int left = (temp >> leftPos) & 1; int bottom = (temp >> bottomPos) & 1; int right = (temp >> rightPos) & 1; // Sum the values of the neighbors int sum = top + left + bottom + right; // Update the cell if all neighbors are 0 and the cell itself is 1 if (sum == 0 && cell == 1) { array &= ~(1ULL << pos); } } } count += (init == array); } return count; } |
## Understanding the Code This function, `count()`, iterates through all possible combinations of an 8x8 grid where each cell can be either 0 or 1. For each combination, it applies a simple rule: if a cell is 1 and all its neighbors (top, bottom, left, right) are 0, then the cell becomes 0. The function counts how many initial combinations remain unchanged after applying this rule. ## Golfing Strategies 1. **Eliminate unnecessary variables:** We can reduce the number of variables by calculating bit positions directly within the conditional statement. 2. **Combine loops:** Instead of separate loops for rows and columns, a single loop can iterate through all 64 cells. 3. **Simplify neighbor checking:** We can streamline the logic for checking neighbor values using bitwise operations. 4. **Remove temporary variable:** The `temp` variable is redundant and can be replaced with direct manipulation of the `array`. ## Golfed Code (Attempt 1)
1 2 3 4 5 6 7 8 9 10 11 12 | int count() { int c=0; for(int i=0;i<1<<16;i++){ long long unsigned a=((i&0xf)<<9)|((i&0xf0)<<(9+4))|((i&0xf00)<<(9+8))|((i&0xf000)<<(9+12)),t=a; for(int j=1;j<63;j++){ int s=((a>>(j-1))&1)+((a>>(j+1))&1)+((a>>(j-8))&1)+((a>>(j+8))&1); if(s==0&&(a>>j)&1) a&=~(1ULL<<j); } c+=(t==a); } return c; } |
1 | int count(){int c=0;for(long long unsigned i=0;i<1<<16;++i){long long unsigned a=((i&0xf)<<9)|((i&0xf0)<<13)|((i&0xf00)<<17)|((i&0xf000)<<21),t=a;for(int j=1;j<63;++j){int s=((a>>(j-1))&1)+((a>>(j+1))&1)+((a>>(j-8))&1)+((a>>(j+8))&1);if(s==0&&(a>>j)&1)a&=~(1ULL<<j);}c+=(t==a);}return c;} |
I extracted the following code from that output:
1 | int count(){int c=0;for(long long unsigned i=0;i<1<<16;++i){long long unsigned a=((i&0xf)<<9)|((i&0xf0)<<13)|((i&0xf00)<<17)|((i&0xf000)<<21),t=a;for(int j=1;j<63;++j){int s=((a>>(j-1))&1)+((a>>(j+1))&1)+((a>>(j-8))&1)+((a>>(j+8))&1);if(s==0&&(a>>j)&1)a&=~(1ULL<<j);}c+=(t==a);}return c;} |
Running the following program:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | int count(){int c=0;for(long long unsigned i=0;i<1<<16;++i){long long unsigned a=((i&0xf)<<9)|((i&0xf0)<<13)|((i&0xf00)<<17)|((i&0xf000)<<21),t=a;for(int j=1;j<63;++j){int s=((a>>(j-1))&1)+((a>>(j+1))&1)+((a>>(j-8))&1)+((a>>(j+8))&1);if(s==0&&(a>>j)&1)a&=~(1ULL<<j);}c+=(t==a);}return c;} #include<stdio.h> #include<stdlib.h> int main() { int answer = count(); int expected = 27488; if (answer != expected) { printf("Wrong answer; got %d instead of %d.\n", answer, expected); exit(1); } printf("All tests passed\n"); } |
Wrong answer; got 22946 instead of 27488.
Testing if the previous output contains the string All tests passed
: False
Resulting in output: True