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. Function Explanation The `count` function iterates through all 65,536 possible 16-bit integers. For each integer, it maps its bits onto an 8x8 grid. It then checks each non-border cell in the grid to determine if a cell with a value of `1` has all four of its immediate neighbors (`top`, `left`, `bottom`, `right`) set to `0`. If such a cell is found, it's cleared (set to `0`). After processing, if the grid remains unchanged (no cells were cleared), the function increments a counter. Finally, the function returns the total count of such integers where no `1` cell has all four neighbors as `0`. ### 2. Strategies to Shorten the Function - **Bit Manipulation Optimization**: Utilize bitwise operations more efficiently to handle neighbor checks and cell updates. - **Loop Unrolling and Variable Reduction**: Minimize the use of loop variables and consolidate nested loops where possible. - **Eliminate Redundant Calculations**: Precompute expressions that repeat within loops. - **Use Shorter Data Types**: Replace `long long unsigned int` with smaller data types if sufficient. - **Reduce Variable Names**: Use single-letter variable names to save space. ### 3. Code-Golfed Function
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++){ unsigned long a=((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21); unsigned long t=a; for(int r=1;r<7;r++) for(int s=1;s<7;s++){ int p=r*8+s, tp=(r-1)*8+s, lp=r*8+s-1, bp=(r+1)*8+s, rp=r*8+s+1; if(((t>>p)&1)&&!((t>>tp)&1)|!((t>>lp)&1)|!((t>>bp)&1)|!((t>>rp)&1)) {a&=~(1UL<<p);} } if(a==((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21)) c++; } return c; } |
1 2 3 4 5 6 7 8 | int count(){ int c=0; unsigned long a,t; for(int i=0;i<65536;i++){ a=((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21); t=a; for(int r=1;r<7;r++) for(int s=1;s<7;s++){int p=r*8+s, tp=(r-1)*8+s, lp=r*8+s-1, bp=(r+1)*8+s, rp=r*8+s+1; if(((t>>p)&1)&&!((t>>tp)&1)&!((t>>lp)&1)&!((t>>bp)&1)&!((t>>rp)&1)) {a&=~(1UL<<p);}} if(a==((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21)) c++;} return c; } |
I extracted the following code from that output:
1 2 3 4 5 6 7 8 9 10 | #include <stdio.h> int count(){ int c=0; unsigned long a,t; for(int i=0;i<65536;i++){ a=((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21); t=a; for(int r=1;r<7;r++) for(int s=1;s<7;s++){int p=r*8+s, tp=(r-1)*8+s, lp=r*8+s-1, bp=(r+1)*8+s, rp=r*8+s+1; if(((t>>p)&1)&&!((t>>tp)&1)&!((t>>lp)&1)&!((t>>bp)&1)&!((t>>rp)&1)) {a&=~(1UL<<p);}} if(a==((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21)) c++;} 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 | #include <stdio.h> int count(){ int c=0; unsigned long a,t; for(int i=0;i<65536;i++){ a=((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21); t=a; for(int r=1;r<7;r++) for(int s=1;s<7;s++){int p=r*8+s, tp=(r-1)*8+s, lp=r*8+s-1, bp=(r+1)*8+s, rp=r*8+s+1; if(((t>>p)&1)&&!((t>>tp)&1)&!((t>>lp)&1)&!((t>>bp)&1)&!((t>>rp)&1)) {a&=~(1UL<<p);}} if(a==((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21)) c++;} 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 65392 instead of 27488.
Testing if the previous output contains the string All tests passed
: False
Resulting in output: False
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. Function Explanation The provided `count` function iterates through all possible 16-bit configurations (from `0` to `65535`). For each configuration: - It maps the 16-bit value into a larger 64-bit array, effectively placing the bits into an 8x8 grid structure. - It then examines each cell (excluding the boundary cells) to check if a cell with a value of `1` has no neighboring `1`s (up, down, left, right). - If a `1` cell has no neighbors, it's turned into a `0`. - After processing all cells, the function increments a counter if the original configuration remains unchanged (i.e., no isolated `1`s were found). In essence, the function counts how many 16-bit configurations have no isolated `1`s in their corresponding 8x8 grid representation. ### 2. Strategies to Shorten the Function Given the function's purpose, we can consider the following methods to reduce its length: - **Variable Naming:** Use single-letter variable names. - **Loop Optimization:** Combine loops or eliminate unnecessary ones. - **Bit Manipulation:** Simplify bit operations and use more compact expressions. - **Removing Redundancies:** Eliminate any redundant assignments or operations. - **Inline Calculations:** Perform calculations directly within conditionals or expressions without intermediate variables. - **Leverage Bitwise Patterns:** Identify patterns that allow batch processing of bits. ### 3. Optimized Function Applying the above strategies, here's a more concise version of the `count` function:
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++){ unsigned long a=((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21); unsigned long t=a; for(int r=1;r<7;r++) for(int s=1;s<7;s++){ int p=r*8+s, tp=(r-1)*8+s, lp=r*8+s-1, bp=(r+1)*8+s, rp=r*8+s+1; if(((t>>p)&1) && !((t>>tp)&1 || (t>>lp)&1 || (t>>bp)&1 || (t>>rp)&1)) a &= ~(1UL<<p); } if(a == ((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21)) c++; } 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++){ unsigned long a=((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21); unsigned long t=a; for(int r=1;r<7;r++) for(int s=1;s<7;s++){ int p=r*8+s, tp=(r-1)*8+s, lp=r*8+s-1, bp=(r+1)*8+s, rp=r*8+s+1; if(((t>>p)&1) && !((t>>tp)&1 || (t>>lp)&1 || (t>>bp)&1 || (t>>rp)&1)) a &= ~(1UL<<p); } if(a == ((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21)) c++; } 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 <stdio.h> int count(){ int c=0; for(int i=0;i<65536;i++){ unsigned long a=((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21); unsigned long t=a; for(int r=1;r<7;r++) for(int s=1;s<7;s++){ int p=r*8+s, tp=(r-1)*8+s, lp=r*8+s-1, bp=(r+1)*8+s, rp=r*8+s+1; if(((t>>p)&1) && !((t>>tp)&1 || (t>>lp)&1 || (t>>bp)&1 || (t>>rp)&1)) a &= ~(1UL<<p); } if(a == ((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21)) c++; } 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 <stdio.h> int count(){ int c=0; for(int i=0;i<65536;i++){ unsigned long a=((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21); unsigned long t=a; for(int r=1;r<7;r++) for(int s=1;s<7;s++){ int p=r*8+s, tp=(r-1)*8+s, lp=r*8+s-1, bp=(r+1)*8+s, rp=r*8+s+1; if(((t>>p)&1) && !((t>>tp)&1 || (t>>lp)&1 || (t>>bp)&1 || (t>>rp)&1)) a &= ~(1UL<<p); } if(a == ((i&15)<<9)|((i&240)<<13)|((i&3840)<<17)|((i&61440)<<21)) c++; } 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 65392 instead of 27488.
Testing if the previous output contains the string All tests passed
: False
Resulting in output: False