题解 | 还是A+B

#include<bits/stdc++.h>
using namespace std;

int main()
{
    int k,l;
    int c;
    while(cin>>k>>l>>c)
    {
        if(k == 0&&l == 0)break;
        string a = to_string(k);
        string b = to_string(l);
        int len1 = a.length();
        int len2 = b.length();
        while(a.length()<c)
        {
            a = "0" + a;
        }
        while(b.length()<c)
        {
            b = "0" + b;
        }
        len1 = a.length()-1;
        len2 = b.length()-1;
        int flag = 0;
        while(c--)
        {
            if(a[len1]!=b[len2])
            {
                cout<<k+l<<endl;
                flag = 1;
                break;
            }
            len1--;len2--;
        }
        if(flag == 0)
        {
            cout<<-1<<endl;
        }
        
    }
    return 0;
}