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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <stdint.h>
  4.  
  5. int n;
  6. int solution_count = 0;
  7. uint32_t col=0, asc=0, desc=0;
  8.  
  9. void backtrack(int i) 
  10. {
  11.     if(i == n) {
  12.         solution_count++;
  13.         return;
  14.     }
  15.     uint32_t mc, md, ma;
  16.     for(int j=0; j != n; j++) {
  17.     	if (col & (mc = 1<<j)) continue;
  18.     	if (desc & (md = 1 << (i+j))) continue;
  19.     	if (asc & (ma = 1 << (15+i-j))) continue;
  20.     	uint32_t oldc = col, oldd = desc, olda = asc;
  21.         col |= mc;
  22.         desc |= md;
  23.         asc |= ma;
  24.         backtrack(i+1);
  25.         col = oldc;
  26.         desc = oldd;
  27.         asc = olda;
  28.     }
  29. }
  30.  
  31. int main() 
  32. { 
  33.     n = 14; 
  34.     backtrack(0);
  35.     printf("%d", solution_count);
  36.     return 0;
  37. }
Success #stdin #stdout 4.04s 2156KB
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stdin 
Standard input is empty
stdout 
365596
https://ideone.com/wXR7hb
language:
C99 (gcc 8.3)
created:
9 years ago
visibility:
public

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