POJ1503: Integer Inquiry(连续多个大整数加法运算)

#include<iostream>
#include<cstring>
using namespace std;
string sum;
const int max_len = 110;
string tool(string a){
    int dif = max_len - a.length();
    string s = "";
    for(int i=0;i<dif;i++){
        s += '0';
    }
    s+=a;
    return s;
}
void solve(string a){
    a = tool(a);
    sum = tool(sum);
    string ssum;
    ssum = tool(ssum);

    for(int i=max_len-1;i>=1;i--){
        int temp = (sum[i] -'0') + (a[i] - '0');
        int c = ssum[i]-'0'+temp;
        ssum[i] = c%10 + '0';
        ssum[i-1] = (ssum[i-1]-'0'+c/10) + '0';
    }
    
    sum = ssum;
}
int main(){
    string a; sum = "";
    while(cin>>a && a!="0"){
        solve(a);
    }
    int i;
    for(i=0;i<max_len;i++){
        if(sum[i]!='0')   break;
     }
     for(int j=i;j<max_len;j++){
         cout<<sum[j];
     }cout<<endl;
}