题解 | #加减乘除#

#include <iostream>
#include <stdio.h>
using namespace std;

int main() {
    int a,b;
    char op;
    int sum = 1;
    cin>>a;
    cin>>op;
    if(op == '!'){
        for(int i = 1; i <= a;i++){
            sum*=i;
        }
        if(a == 0){
            cout<<1<<endl;
        }
        cout<<sum<<endl;
    }else{
        cin>>b;
        if(b == 0 || a==0){
            cout<<"error"<<endl;
        }
        switch(op){
            case '*':cout<<a * b<<endl;break;
            case '%':cout<<a % b<<endl;break;
            case '+':cout<<a + b<<endl;break;
            case '-':cout<<a - b<<endl;break;
            case '/':cout<<a / b<<endl;break;
        }
    }
    return 0;
}
// 64 位输出请用 printf("%lld")