2020 CCPC Qinhuangdao Station Problem A. Greeting from Qinhuangdao

2020 CCPC Qinhuangdao Station Problem A. Greeting from Qinhuangdao

Title:

There are r red balloons and s blue balloons. Two balloons are randomly selected from these balloons. The probability that the two selected balloons are red balloons is expressed as a score. If the probability is 0, the output is 0/1

analysis:

This is a very friendly sign-in question,
which can be simplified by using the permutation and combination formula: be
careful not to forget the points

Code:

#include<bits/stdc++.h>
using namespace std;
int main()
{
    
    
    int t,r,b;
    int x,y;
    int temp;
    scanf("%d",&t);
    for(int i=0;i<t;i++)
    {
    
    
        scanf("%d%d",&r,&b);
        x=r*(r-1);//公式化简可得
        y=(r+b)*(r+b-1);
        temp=__gcd(x,y);//求最大公约数
        x=x/temp;//分数化简
        y=y/temp;
        if(x==0)//输出
            printf("Case #%d: 0/1\n",i+1);
        else
            printf("Case #%d: %d/%d\n",i+1,x,y);
    }
    return 0;
}

Result :