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; } |
1. **Explanation:** The function `count` iterates through all possible configurations of a 8x8 grid where each cell can be either 0 or 1 (represented by bits in a 64-bit integer). For each configuration, it simulates a single step of a cellular automaton rule. Specifically, if a cell is 'on' (1) and all its orthogonal neighbors (up, down, left, right) are 'off' (0), the cell turns 'off' (0) in the next step. The function counts the number of configurations where no cells change state after this single step application, meaning the configuration is stable under this rule. The initial configuration is represented by the variable `init`, and the configuration after the rule application is represented by `array`. 2. **Shortening Strategies:** * **Bit Manipulation:** Leverage bitwise operations more efficiently to avoid explicit loop calculations of neighbor positions. * **Simplified Loops:** Combine nested loops and use bit shifts for neighbor checking. * **Eliminate Redundancy:** Remove unnecessary temporary variables. * **Constants:** Use `constexpr` to define constants and potentially enable compile-time optimizations. 3. **Shorter Code (Attempt 1):**
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | int count() { constexpr int R = 8, C = 8; int cnt = 0; for (unsigned long long i = 0; i < (1ULL << (R * C)); ++i) { unsigned long long init = i, arr = i; for (int j = C + 1; j < (R - 1) * C - 1; ++j) { if ((arr >> j) & 1 && !(((arr >> (j - 1)) & 1) | ((arr >> (j + 1)) & 1) | ((arr >> (j - C)) & 1) | ((arr >> (j + C)) & 1))) { arr &= ~(1ULL << j); } } cnt += (init == arr); } return cnt; } |
1 2 3 4 5 6 7 8 9 10 11 12 | int count() { constexpr int R = 8, C = 8; int cnt = 0; for (unsigned long long i = 0; i < (1ULL << (R * C)); ++i) { unsigned long long arr = i; for (int j = C + 1; j < (R - 1) * C - 1; ++j) if ((arr >> j) & 1 && !((arr >> (j - 1) | arr >> (j + 1) | arr >> (j - C) | arr >> (j + C)) & 1)) arr &= ~(1ULL << j); cnt += (i == arr); // Directly compare with i } return cnt; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | ++ #include <iostream> int count() { constexpr int R = 8, C = 8; int cnt = 0; for (unsigned long long i = 0; i < (1ULL << (R * C)); ++i) { unsigned long long arr = i; for (int j = C + 1; j < (R - 1) * C - 1; ++j) if ((arr >> j) & 1 && !((arr >> (j - 1) | arr >> (j + 1) | arr >> (j - C) | arr >> (j + C)) & 1)) arr &= ~(1ULL << j); cnt += (i == arr); // Directly compare with i } return cnt; } |
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 | ++ #include <iostream> int count() { constexpr int R = 8, C = 8; int cnt = 0; for (unsigned long long i = 0; i < (1ULL << (R * C)); ++i) { unsigned long long arr = i; for (int j = C + 1; j < (R - 1) * C - 1; ++j) if ((arr >> j) & 1 && !((arr >> (j - 1) | arr >> (j + 1) | arr >> (j - C) | arr >> (j + C)) & 1)) arr &= ~(1ULL << j); cnt += (i == arr); // Directly compare with i } return cnt; } #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"); } |
main.c:1:1: error: expected identifier or '(' before '++' token
1 | ++
| ^~
main.c:2:10: fatal error: iostream: No such file or directory
2 | #include <iostream>
| ^~~~~~~~~~
compilation terminated.
main.sh: line 2: ./a.out: No such file or directory
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; } |
1. **Explanation:** The function `count` iterates through all possible configurations of a 8x8 grid (represented by a 64-bit integer, where each bit corresponds to a cell). For each configuration, it simulates a single step of a cellular automaton rule where a cell becomes 0 if it's currently 1 and all its orthogonal neighbors (top, bottom, left, right) are 0. The outer cells of the grid are not updated. The function counts the number of configurations that remain unchanged after this single step. 2. **Shortening Strategies:** * **Bitwise operations for neighbor checking:** Instead of calculating neighbor positions and extracting individual bits, use bitwise shifts and masks to directly check neighbors. * **Eliminate redundant variables and calculations:** Remove unnecessary intermediate variables and combine calculations. * **Compact loops:** Use shorter loop conditions and increment steps. * **Precalculate constants:** Precalculate frequently used constants like masks. 3. **Shorter Function:**
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | int count() { int c = 0; for (long long unsigned i = 0; i < 1LL << 16; i++) { long long unsigned a = ((i & 0xf) << 9) | ((i & 0xf0) << 13) | ((i & 0xf00) << 17) | ((i & 0xf000) << 21); long long unsigned init = a; for (int j = 9; j < 55; j++) { if ((a >> j) & 1 && !(((a >> (j - 8)) & 1) | ((a >> (j - 1)) & 1) | ((a >> (j + 1)) & 1) | ((a >> (j + 8)) & 1))) { a &= ~(1LL << j); } } c += (init == a); } return c; } |
1 2 3 4 5 6 7 8 9 10 11 12 | int count() { int c = 0; for (unsigned long long a, i = 0; i < 1LL << 16; i++) { a = ((i & 0xf) << 9) | ((i & 0xf0) << 13) | ((i & 0xf00) << 17) | ((i & 0xf000) << 21); unsigned long long init = a; for (int j = 9; j < 55; j++) if ((a >> j) & 1 && !(((a >> (j - 8)) | (a >> (j - 1)) | (a >> (j + 1)) | (a >> (j + 8)))&1)) a &= ~(1LL << j); c += (init == a); } return c; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | #include <stdio.h> int count() { int c = 0; for (unsigned long long a, i = 0; i < 1LL << 16; i++) { a = ((i & 0xf) << 9) | ((i & 0xf0) << 13) | ((i & 0xf00) << 17) | ((i & 0xf000) << 21); unsigned long long init = a; for (int j = 9; j < 55; j++) if ((a >> j) & 1 && !(((a >> (j - 8)) | (a >> (j - 1)) | (a >> (j + 1)) | (a >> (j + 8)))&1)) a &= ~(1LL << j); c += (init == 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 19 20 21 22 23 24 25 26 27 28 29 30 31 | #include <stdio.h> int count() { int c = 0; for (unsigned long long a, i = 0; i < 1LL << 16; i++) { a = ((i & 0xf) << 9) | ((i & 0xf0) << 13) | ((i & 0xf00) << 17) | ((i & 0xf000) << 21); unsigned long long init = a; for (int j = 9; j < 55; j++) if ((a >> j) & 1 && !(((a >> (j - 8)) | (a >> (j - 1)) | (a >> (j + 1)) | (a >> (j + 8)))&1)) a &= ~(1LL << j); c += (init == 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
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; } |
1. **Explanation:** The `count` function calculates the number of 8x8 bit patterns where no isolated '1' bit (surrounded by '0' bits) changes to '0' in a single step of a simplified cellular automaton rule. The rule is: a cell becomes '0' if and only if it is currently '1' and all its orthogonal neighbors (up, down, left, right) are '0'. The outer border cells are not updated. 2. **Shortening Strategies:** * **Bit Manipulation:** Leverage bitwise operations more effectively to avoid explicit indexing calculations. * **Loop Simplification:** Combine loops and use bit shifts instead of multiplication. * **Eliminate Redundancy:** Remove unnecessary variables and calculations. * **Pre-compute Neighbor Masks:** Instead of calculating neighbor positions each time, pre-calculate masks for each cell's neighbors. 3. **Shorter Function:**
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | int count() { int c = 0; for (int i = 0; i < 65536; i++) { unsigned long long a = ((i & 15) << 9) | ((i & 240) << 13) | ((i & 3840) << 17) | ((i & 61440) << 21); unsigned long long init = a; for (int j = 1; j < 7; ++j) { for (int k = 1; k < 7; ++k) { int pos = j * 8 + k; if (((a >> pos) & 1) && !(((a >> (pos - 1)) & 1) | ((a >> (pos + 1)) & 1) | ((a >> (pos - 8)) & 1) | ((a >> (pos + 8)) & 1))) { a &= ~(1ULL << pos); } } } c += (init == a); } return c; } |
1 | int count(){int c=0;for(int i=0;i<65536;++i){unsigned long long a=((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21),b=a;for(int j=9;j<57;j+=8)for(int k=1;k<7;++k){int p=j+k;if((a>>p)&1&&!((a>>(p-1))&1|(a>>(p+1))&1|(a>>(p-8))&1|(a>>(p+8))&1))a&=~(1ULL<<p);}c+=(b==a);}return c;} |
I extracted the following code from that output:
1 2 | ++ int count(){int c=0;for(int i=0;i<65536;++i){unsigned long long a=((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21),b=a;for(int j=9;j<57;j+=8)for(int k=1;k<7;++k){int p=j+k;if((a>>p)&1&&!((a>>(p-1))&1|(a>>(p+1))&1|(a>>(p-8))&1|(a>>(p+8))&1))a&=~(1ULL<<p);}c+=(b==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 19 | ++ int count(){int c=0;for(int i=0;i<65536;++i){unsigned long long a=((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21),b=a;for(int j=9;j<57;j+=8)for(int k=1;k<7;++k){int p=j+k;if((a>>p)&1&&!((a>>(p-1))&1|(a>>(p+1))&1|(a>>(p-8))&1|(a>>(p+8))&1))a&=~(1ULL<<p);}c+=(b==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"); } |
main.c:1:1: error: expected identifier or '(' before '++' token
1 | ++
| ^~
main.c: In function 'main':
main.c:12:14: warning: implicit declaration of function 'count' [-Wimplicit-function-declaration]
12 | int answer = count();
| ^~~~~
main.sh: line 2: ./a.out: No such file or directory
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; } |
1. **Explanation:** The function `count` calculates the number of 8x8 bit patterns (represented as a 64-bit integer) where no set bit (1) is surrounded by four unset bits (0s) unless the set bit is on the border. It iterates through all possible 8x8 bit patterns (2^16 possibilities because only the inner 6x6 grid can vary, the outer layer is implicitly 0). For each pattern, it checks the inner 6x6 grid. If a set bit within this inner grid has all four neighbors unset, it clears that bit. Finally, it increments the counter if the original pattern remains unchanged after this process (meaning no inner bits were cleared). 2. **Shortening Strategies:** * **Bit Manipulation Tricks:** We can use bitwise operations more efficiently to check neighbors. * **Loop Simplification:** We can potentially simplify the nested loops. * **Eliminate Redundancy:** The code recalculates bit positions repeatedly. We can optimize this. * **Concise Variable Names:** Use shorter variable names. * **Remove Unnecessary Variables:** Some variables can be eliminated. 3. **Shorter Function:**
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | int count() { int c = 0; for (int i = 0; i < 65536; ++i) { long long a = ((i & 15) << 9) | ((i & 240) << 13) | ((i & 3840) << 17) | ((i & 61440) << 21); long long init = a; for (int r = 1; r < 7; ++r) { for (int col = 1; col < 7; ++col) { int p = r * 8 + col; if ((a >> p) & 1 && !(((a >> (p - 1)) & 1) | ((a >> (p + 1)) & 1) | ((a >> (p - 8)) & 1) | ((a >> (p + 8)) & 1))) { a &= ~(1ULL << p); } } } c += (init == a); } return c; } |
1 2 3 4 5 6 7 8 9 10 11 12 13 | int count() { int c = 0; for (int i = 0; i < 65536; i++) { long long a = (i & 15) << 9 | (i & 240) << 13 | (i & 3840) << 17 | (i & 61440) << 21; long long init = a; for (int r = 9; r < 55; r += 8) for (int p = r + 1; p < r + 7; p++) if ((a >> p) & 1 && !((a >> (p - 1) | a >> (p + 1) | a >> (p - 8) | a >> (p + 8)) & 1)) a &= ~(1ULL << p); c += (init == a); } return c; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | ++ int count() { int c = 0; for (int i = 0; i < 65536; i++) { long long a = (i & 15) << 9 | (i & 240) << 13 | (i & 3840) << 17 | (i & 61440) << 21; long long init = a; for (int r = 9; r < 55; r += 8) for (int p = r + 1; p < r + 7; p++) if ((a >> p) & 1 && !((a >> (p - 1) | a >> (p + 1) | a >> (p - 8) | a >> (p + 8)) & 1)) a &= ~(1ULL << p); c += (init == 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 19 20 21 22 23 24 25 26 27 28 29 30 31 | ++ int count() { int c = 0; for (int i = 0; i < 65536; i++) { long long a = (i & 15) << 9 | (i & 240) << 13 | (i & 3840) << 17 | (i & 61440) << 21; long long init = a; for (int r = 9; r < 55; r += 8) for (int p = r + 1; p < r + 7; p++) if ((a >> p) & 1 && !((a >> (p - 1) | a >> (p + 1) | a >> (p - 8) | a >> (p + 8)) & 1)) a &= ~(1ULL << p); c += (init == 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"); } |
main.c:1:1: error: expected identifier or '(' before '++' token
1 | ++
| ^~
main.c: In function 'main':
main.c:24:14: warning: implicit declaration of function 'count' [-Wimplicit-function-declaration]
24 | int answer = count();
| ^~~~~
main.sh: line 2: ./a.out: No such file or directory
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; } |
1. **Explanation:** The function `count` iterates through all possible 8x8 bit arrays (represented by a 64-bit integer). For each array, it simulates a single step of a cellular automaton rule. Specifically, if a cell is 'on' (1) and all its orthogonal neighbors (up, down, left, right) are 'off' (0), the cell turns 'off' (0) in the next step. The function counts how many initial arrays remain unchanged after this single step, meaning no cells were turned off. The initial configuration only sets bits on the inner 6x6 grid, ensuring border cells are always 0. 2. **Shortening Strategies:** * **Bit Manipulation Tricks:** We can use bit manipulation to more efficiently check neighbors. * **Eliminate Redundant Variables:** Many intermediate variables can be removed by combining operations. * **Loop Optimization:** The nested loops can be optimized by pre-calculating certain values. * **Simplified Logic:** The conditional logic can be streamlined using bitwise operators. * **Constants:** Pre-calculate constants instead of repeating calculations. 3. **Shorter Function:**
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | int count() { int c = 0; for (int i = 0; i < 1 << 16; i++) { long long a = ((i & 0xf) << 9) | ((i & 0xf0) << 13) | ((i & 0xf00) << 17) | ((i & 0xf000) << 21); long long init = a; for (int j = 8; j < 56; j++) { if ((a >> j) & 1 && !(((a >> (j - 8)) & 1) | ((a >> (j + 8)) & 1) | ((a >> (j - 1)) & 1) | ((a >> (j + 1)) & 1) )) { a &= ~(1ULL << j); } } c += (init == a); } return c; } |
1 2 3 4 5 6 7 8 9 10 11 12 | int count() { int c = 0; for (unsigned i = 0; i < 1 << 16; ++i) { unsigned long long a = (i & 0xf) << 9 | (i & 0xf0) << 13 | (i & 0xf00) << 17 | (i & 0xf000) << 21; unsigned long long init = a; for (int j = 8; j < 56; ++j) if ((a >> j) & 1 && !((a >> (j - 8) | a >> (j + 8) | a >> (j - 1) | a >> (j + 1)) & 1)) a &= ~(1ULL << j); c += (init == a); } return c; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | ++ #include <iostream> int count() { int c = 0; for (unsigned i = 0; i < 1 << 16; ++i) { unsigned long long a = (i & 0xf) << 9 | (i & 0xf0) << 13 | (i & 0xf00) << 17 | (i & 0xf000) << 21; unsigned long long init = a; for (int j = 8; j < 56; ++j) if ((a >> j) & 1 && !((a >> (j - 8) | a >> (j + 8) | a >> (j - 1) | a >> (j + 1)) & 1)) a &= ~(1ULL << j); c += (init == 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 19 20 21 22 23 24 25 26 27 28 29 30 31 32 | ++ #include <iostream> int count() { int c = 0; for (unsigned i = 0; i < 1 << 16; ++i) { unsigned long long a = (i & 0xf) << 9 | (i & 0xf0) << 13 | (i & 0xf00) << 17 | (i & 0xf000) << 21; unsigned long long init = a; for (int j = 8; j < 56; ++j) if ((a >> j) & 1 && !((a >> (j - 8) | a >> (j + 8) | a >> (j - 1) | a >> (j + 1)) & 1)) a &= ~(1ULL << j); c += (init == 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"); } |
main.c:1:1: error: expected identifier or '(' before '++' token
1 | ++
| ^~
main.c:2:10: fatal error: iostream: No such file or directory
2 | #include <iostream>
| ^~~~~~~~~~
compilation terminated.
main.sh: line 2: ./a.out: No such file or directory
Testing if the previous output contains the string All tests passed
: False
Resulting in output: True