题解 | 判断成绩等级

#include <iostream>
using namespace std;

int main() {
    
    int score;
    cin >> score;
    if(score<0 or score>100) {
        cout<<"成绩不合法";
    }
    else{
        if(score<60){
            cout<<"差";
        }
        else{
            if(score<70){
                cout<<"及格";
            }
            else{
                if(score<80){
                    cout<<"中";
                }
                else{
                    if(score<90){
                    cout<<"良";
                    }
                    else{
                         cout<<"优秀";}

                 }

                }    
            }
    }
    return 0;
}