Uva 412 - Pi

水数论

gcd+模拟

1Y

#include<stdio.h>#include<cmath>int gcd(int x,int y){if(x<y)return gcd(y,x);if(y==0)return x;return gcd(y,x%y);} int a[60];int main(){int n;while(scanf("%d",&n)!=EOF&&n){int i,j,res=0;for(i=1;i<=n;i++)scanf("%d",&a[i]);for(i=1;i<=n;i++)for(j=i+1;j<=n;j++)if(gcd(a[i],a[j])==1)res++;int m=(n-1)*n/2;double x=res/(double)m;if(res)printf("%.6lf\n",sqrt(6/x));else printf("No estimate for this data set.\n");}return 0;}