蓝桥杯之夺冠取宝

#include<bits/stdc++.h>

using namespace std;

int main()
{
    double ab_cd = 0.1*0.2*0.3+0.1*0.8*0.5; // ab_cd 代表  (a vs b)a  (a vs c)+(a vs d)=a的概率  
    double ac_bd = 0.3*0.4*0.1+0.3*0.6*0.5; // ac_bd 代表  (a vs c)a  (a vs b)+(a vs d)=a的概率  
    double ad_bc = 0.5*0.7*0.1+0.5*0.3*0.3; // ad_bc 代表  (a vs d)a  (a vs b)+(a vs c)=a的概率  
    double sum = 0; // 总计
    int n = 100000; // 循环次数  
    for(int i=0;i<n;i++){    // 10万次模拟  
        int r = rand()%3;
        switch(r)
        {  
            case 0: sum += ab_cd; break;  
            case 1: sum += ac_bd; break;  
            case 2: sum += ad_bc; break;  
        }  
    }  
        cout<< sum/n;
        return 0;
}