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#include <stdio.h>
#include <stdlib.h>
long long Pn(int n)
{
return (long long)n*(long long)(3*n-1)/2;
}
#define MAXSIZE (1<<22)
long long P[MAXSIZE];
int comp(const void *a, const void *b)
{
long long aa = *(long long*)a;
long long bb = *(long long*)b;
if (aa < bb)
return -1;
if (aa > bb)
return 1;
return 0;
}
int main()
{
int i, j;
int range = (1<<15);
for (i = 1; i < range; i++)
P[i] = Pn(i);
/* i < 257 is impossible when searching with range=(1<<15) */
/* i < 725 is impossible with range=(1<<18) */
/* i < 1449 is impossible with range=(1<<20) */
for (i = 1; i < range; i++) {
long long diff = P[i];
for (j = 1; j < range - 1; j++) {
long long Pj = P[j];
long long Pk = Pj + diff;
long long Pjk = Pj + Pk;
if (Pk < P[j+1])
break;
while (Pjk > P[range-1]) {
int newrange = range * 2;
int r;
for (r = range; r < newrange; r++)
P[r] = Pn(r);
range = newrange;
}
if (!bsearch(&Pk, P+1, range-1, sizeof(long long), comp))
continue;
if (!bsearch(&Pjk, P+1, range-1, sizeof(long long), comp))
continue;
printf("i = %d, D = %lld, j = %d, P[j] = %lld\n", i, diff, j, Pj);
/* i = 1912, D = 5482660, j = 1020, P[j] = 1560090 */
return 0;
}
printf("i = %d\n", i);
}
}
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