Pythagorean Triple Numbers (Marijn Heule)

ptn-encode.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main (int argc, char** argv) {
  unsigned int a, b, c, max, offset = 0, nVars = 0, nClauses = 0;

  if (argc < 2) {
    printf ("run using ./ptn-encode MAX [OFFSET=0]\n"); exit (0); }

  max = atoi (argv[1]);
  if (argc > 2) offset = atoi(argv[2]);

  for (a = 1; a <= max; a++)
    for (b = a; (a*a + b*b) <= (max * max); b++) {
      c = sqrt(a*a + b*b);
      if ((c*c) == (a*a + b*b)) {
        nClauses += 2;
        if (c > nVars) nVars = c; } }

  printf ("p cnf %i %i\n", nVars + offset, nClauses);

  for (a = 1; a <= max; a++)
    for (b = a; (a*a + b*b) <= (max*max); b++) {
      c = sqrt(a*a + b*b);
      if ((c*c) == (a*a + b*b)) {
        printf ("%i %i %i 0\n",  a + offset,  b + offset,  c + offset);
        printf ("%i %i %i 0\n", -a - offset, -b - offset, -c - offset); } } }