题解 | 加减乘除

#include<iostream>
#include<cstdio>
#include<string>
using namespace std;
long long Function(int n){
    if(n==1){
        return 1;
    }else{
        return n*Function(n-1);
    }
}
int main(){
    int n=0;
    while(scanf("%d",&n) != EOF){
        getchar();
        char a;
        scanf("%c",&a);
        if(a == '!'){
            cout<<Function(n)<<endl;
        }else if(a=='/'){
            int m =1;
            scanf("%d",&m);
            if(m==0){
                cout<<"error"<<endl;
            }else{
                cout<<n/m<<endl;
            }
        }else if(a=='%'){
            int m=0;
            scanf("%d",&m);
            if(m==0){
                cout<<"error"<<endl;
            }else{
                cout<<n%m<<endl;
            }
        }else if(a=='+'){
            int m=0;
            scanf("%d",&m);
            cout<<m+n<<endl;
        }else if(a=='-'){
            int m=0;
            scanf("%d",&m);
            cout<<n-m<<endl;
        }else if(a=='*'){
            int m=0;
            scanf("%d",&m);
            cout<<m*n<<endl;
        }
    }
    return 0;
}