zoj 1337 Pi

#include<stdio.h>#include<stdlib.h>#include<math.h>int prime(int a,int b){int i;for(i = 2;i<=b;i++)if(a % i == 0 && b % i == 0) return 0;    return 1;}int main(){int n,i,j,sum;double pi;int *p;while(scanf("%d",&n)&& n!= 0){p = (int *)malloc(sizeof(int));sum = 0;for(i = 0;i<n;i++)scanf("%d",&p[i]);for(i = 0;i<n;i++)for(j = i+1;j<n;j++)if(p[i]>p[j]){if(prime(p[i],p[j])) sum++;}else {if(prime(p[j],p[i])) sum++;}if(sum){pi = sqrt(3*1.0*n*(n - 1)/sum);printf("%.6lf\n",pi);    }    else printf("No estimate for this data set.\n");}}