#include 
     
      using namespace std;//概率计算PIint 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;}