概率法计算PI

#include <iostream>
using namespace std;
//概率计算PI
int main()
{
    int inside=0;
    double val;
    int i;
    for ( i=0; i<100000000; i++)
    {
        double x = (double)(rand())/RAND_MAX;
        double y = (double)(rand())/RAND_MAX;
        if ( (x*x + y*y) <= 1.0 )
        {
            inside++;
        }
    }
    val = (double)inside / i;
    printf("PI = %.4g\n", val*4);
    return 0;
}