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; } |
### Explanation of the Function The function `count` iterates over all possible 16-bit integers (`i` from `0` to `2^16 - 1`). For each integer `i`, it constructs a 64-bit unsigned integer `array` by shifting and combining the nibbles (4-bit chunks) of `i` into specific positions. This `array` represents an 8x8 grid of bits. The function then simulates a cellular automaton on this grid. For each cell in the grid (excluding the border cells), it checks the values of its four neighbors (top, left, bottom, right). If all four neighbors are `0` and the cell itself is `1`, the cell is set to `0`. After processing all cells, the function checks if the grid has changed. If the grid remains unchanged, it increments the `count`. Finally, the function returns the total count of grids that remained unchanged after the simulation. ### Ways to Make the Function Shorter 1. **Remove Unnecessary Variables**: Variables like `ROWS` and `COLS` can be replaced with their constant values. 2. **Simplify Bit Manipulation**: The bit manipulation to construct `array` can be simplified. 3. **Combine Loops**: The nested loops can be combined or simplified. 4. **Use Shorter Variable Names**: Use single-letter variable names where possible. 5. **Remove Comments**: Comments can be removed to save space. 6. **Inline Calculations**: Inline calculations to reduce the number of lines. ### Shortened Function Here’s the function shortened to less than 300 bytes:
1 | int count(){int c=0;for(long long i=0;i<1<<16;i++){long long a=((i&0xf)<<9)|((i&0xf0)<<13)|((i&0xf00)<<17)|((i&0xf000)<<21),t=a;for(int j=9;j<55;j++){int s=((t>>(j-8))&1)+((t>>(j-1))&1)+((t>>(j+8))&1)+((t>>(j+1))&1);if(s==0&&(t>>j)&1)a&=~(1ULL<<j);}c+=(t==a);}return c;} |
1 | int count(){int c=0;for(long long i=0;i<1<<16;i++){long long a=((i&0xf)<<9)|((i&0xf0)<<13)|((i&0xf00)<<17)|((i&0xf000)<<21),t=a;for(int j=9;j<55;j++){int s=((t>>(j-8))&1)+((t>>(j-1))&1)+((t>>(j+8))&1)+((t>>(j+1))&1);if(s==0&&(t>>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 i=0;i<1<<16;i++){long long a=((i&0xf)<<9)|((i&0xf0)<<13)|((i&0xf00)<<17)|((i&0xf000)<<21),t=a;for(int j=9;j<55;j++){int s=((t>>(j-8))&1)+((t>>(j-1))&1)+((t>>(j+8))&1)+((t>>(j+1))&1);if(s==0&&(t>>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 i=0;i<1<<16;i++){long long a=((i&0xf)<<9)|((i&0xf0)<<13)|((i&0xf00)<<17)|((i&0xf000)<<21),t=a;for(int j=9;j<55;j++){int s=((t>>(j-8))&1)+((t>>(j-1))&1)+((t>>(j+8))&1)+((t>>(j+1))&1);if(s==0&&(t>>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