gistfile1.c

#include <stdio.h>

#define R 10000

int main()
{
    int inCircleCount = 0;
    int x, y;
    for (y = 0; y < R; ++y)
	for (x = 0; x < R; ++x)
	    if (x*x + y*y < R*R)
		++inCircleCount;
    printf("PI: %f\n", (double)inCircleCount / (R * R) * 4);
    return 0;
}