POJ1503 - Integer Inquiry

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

int main()
{
    int N = 400;
    //input用来存储输入数据
    int input[N][N];
    memset(input, 0, sizeof(input));
    string s;
    int num = 0;
    //将接收的string类型转化成数组，便于处理
    while (cin >> s)
    {
        if (s == "0")
            break;
        else
        {
            for (int i = s.size(), j = N-1; i > 0; i--, j--)
            {
                input[num][j] = s[i-1] - 48;
            }
        }
        num++;
    }

    //sum数组用来处理求和
    int sum[N];
    memset(sum, 0, sizeof(sum));
    for (int i = 0; i < N; i++)
    {
        for (int j = 0; j < N; j++)
        {
            sum[i] += input[j][i];
        }
    }

    for (int i = N-1; i >=0; i--)
    {
        sum[i-1] += sum[i]/10;
        sum[i] = sum[i]%10;
    }

    int high = 0;
    for (int i = 0; i < N; i++)
    {
        if (sum[i] != 0)
        {
            high = i;
            break;
        }
    }

    for (int j = high; j < N; j++)
    {
        cout << sum[j];
    }
    cout << endl;

    return 0;
}