uva 424 Integer Inquiry

#include<iostream>

#include<cctype>

#include<cstdlib>

#include<cstring>

using namespace std;



int main(){

    char a[110][110];

    int result[110];

    int num = 0,index;

    memset(a,'a',sizeof(a));        //没有初始化，wa 了好几次

    memset(result,0,sizeof(result));

    string s;

    while(cin >> s){

        if(s[0] == '0')

            break;

        index = 0;

        for(int i = s.length() - 1; i >= 0; i--)  //将读入的字符串反转，低位在前

            a[num][index++] = s[i];

        num++;

    }

    int c = 0;

    for(int i = 0; i < 110; i++){

        int sum = 0;

        for(int j = 0; j < num; j++){

            if(isdigit(a[j][i]))

                sum += a[j][i] - '0';

        }

        sum += c;

        c = sum / 10;

        result[i] = sum % 10;

    }

    int k;

    for(k = 109; result[k] == 0; k--);           //忽略前导0

    for(;k>=0;k--)

        cout << result[k];

    cout << endl;

    return 0;

}