POJ 2389

#include <iostream>
#include <algorithm>
#include <string>
#define MAXN 300
using namespace std;

int tem[MAXN];

void big_int_mul(string a,string b,string & ans);

int main()
{
    //freopen("acm.acm","r",stdin);    
    string a;
    string b;
    string ans;
    cin>>a>>b;
    big_int_mul(a,b,ans);
    cout<<ans<<endl;
}

void big_int_mul(string a,string b,string & ans)
{
    int len_1 = a.length();
    int len_2 = b.length();
    int len = a.length() + b.length();
    int i;
    int j;
    for(i = 0; i < len_1; ++ i)
    {
        for(j = 0; j < len_2; ++ j)
        {
            tem[i+j+1] += (a[i]-'0')*(b[j] - '0');
        }
    }
    for(i = len - 1; i > 0; -- i)
    {
        if(tem[i] >= 10)
        {
            tem[i-1] += tem[i]/10;
            tem[i] %= 10;
        }
    }
    j = 0; 
    while(tem[j] == 0)
    {
        ++ j;
    }
    
    for(; j < len; ++ j)
    {
        ans += char(tem[j]+'0');
    }
}