2021-04-12

b简单的概率问题
注意结果约分就行了

#include<iostream>
using namespace std;
int gcd(int x,int y)
{
    while(y) y^=x^=y^=x%=y;
    return x;
}
int main()
{
    int t;
    int a,v,i,n;
    char s[200];
    while(cin>>t)
    {
        a=v=i=n=0;
        cin>>s+1;
        for(int j=1;j<=t;j++)
        {
            if(s[j]=='a') a++;
            else if(s[j]=='v') v++;
            else if(s[j]=='i') i++;
            else if(s[j]=='n') n++;
        }
        if(!a||!v||!i||!n) cout<<"0/1"<<endl;
        else
        {
            int l=a*v*i*n;
            int r=t*t*t*t;
            int c=gcd(l,r);
            l/=c,r/=c;
            cout<<l<<'/'<<r<<endl;
        }
    }
}