题解 | 数字反转

#include <iostream>
#include <algorithm>
using namespace std;
string add(string a, string b) {
    reverse(a.begin(), a.end());
    reverse(b.begin(), b.end());
    int t = 0;
    for (int i = 0; i < a.size(); ++i) {
        int x1 = a[i] - '0';
        int x2 = b[i] - '0';
        int temp = x1 + x2 + t;
        if (temp > 9) {
            t = 1;
        }
        a[i] = temp % 10+'0';
    }
    if (t == 1) {
        a += '1';
    }
    reverse(a.begin(), a.end());
    return a;
}
int main() {
    string a, b;
    while (cin >> a >> b) {
        int Max = max(a.size(), b.size());
        reverse(a.begin(), a.end());
        reverse(b.begin(), b.end());
        string ret1 = add(a, b);
        a.resize(Max, '0');
        b.resize(Max, '0');
        reverse(a.begin(), a.end());
        reverse(b.begin(), b.end());
        string ret2 = add(a, b);
        reverse(ret1.begin(),ret1.end());
        if (ret1 == ret2) {
            cout << ret1 << endl;
        }
        else {
            cout << "NO" << endl;
        }
    }
}
// 64 位输出请用 printf("%lld")