编程一小时

#include<iostream>
using namespace std;
int main()
{
    int n, i = 0;
    double a, b;
    char o;
    int pos = 0;
    double res, diff, diff1;
    cin>>n;
    while(i < n)
    {
        cin>>a>>o>>b;
        switch (o)
        {
            case '+': res = a + b; break;
            case '-': res = a - b; break;
            case '*': res = a * b; break;
            case '/': res = a / b; break;
        };
        if(res > 9)
            diff1 = res - 9;
        else
            diff1 = 9 - res;

        if(i == 0)
        {
            diff = diff1;
        }
        if(diff > diff1)
        {
            diff = diff1;
            pos = i + 1;
        }
        i++;
    }
    cout<<pos;
    return 0;
}