Pi

来源：互联网发布：软件开发费用计算方法编辑：程序博客网时间：2024/04/20 11:12

题意：给你n个数字，让你求出其中任意两个数互质所占的比重，求出；根据题意6/ ^2 == (互质组数）/（总数C（N，2 ））；

其次，控制精度即可

// File Name: 1059.cpp// Author: bo_jwolf// Created Time: 2014年02月03日 星期一 20时45分14秒#include<vector>#include<list>#include<map>#include<set>#include<deque>#include<stack>#include<bitset>#include<algorithm>#include<functional>#include<numeric>#include<utility>#include<sstream>#include<iostream>#include<iomanip>#include<cstdio>#include<cmath>#include<cstdlib>#include<cstring>#include<ctime>using namespace std;const int maxn =100005;int num[ maxn ];int Gcd( int a, int b ){return b == 0 ? a : Gcd( b, a % b );}int main(){int n;while( cin >> n ){if( !n )break;for( int i = 0; i < n; ++i )cin >> num[ i ];int ans = 0;for( int i = 0; i < n; ++i ){for( int j = 0; j < i; ++j ){if( Gcd( num[ i ], num[ j ] ) == 1 ){ans++;}}}double temp = 2.0 * ans / n / ( n - 1 );if( ans ){printf( "%.6lf\n", sqrt( 6.0 / temp ) );}else{puts( "No estimate for this data set." );}}return 0;}

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