此题使用多分支判断即可

AC代码如下：

#include<bits/stdc++.h>
#define int long long
using namespace std;
int n;
signed main(){
    cin>>n;
    if(n>=15) cout<<"qingnianzu";
    else if(n>=11) cout<<"shaonianzu";
    else cout<<"ertongzu";

    return 0;
}

作者不易，如期题解对您有用，请点个赞😃

#include<bits/stdc++.h>
#define int long long
using namespace std;
int n;
signed main(){
    cin>>n;
    if(n>=15) cout<<"qingnianzu";
    else if(n>=11) cout<<"shaonianzu";
    else cout<<"ertongzu";

    return 0;
}