Solution of 10106 - Product

Problem Description
source:https://uva.onlinejudge.org/external/101/10106.html

The problem is to multiply two integers X, Y . (0 ≤ X, Y < 10²⁵⁰)

Input 

The input will consist of a set of pairs of lines. Each line in pair contains one multiplyer. 

Output 

For each input pair of lines the output line should consist one integer the product.

Sample Input 

12 
12 
2 
222222222222222222222222 

Sample Output 

144 
444444444444444444444444

Solution:

#include <algorithm>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <deque>
#include <fstream>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
#include<stdio.h>
#include<stdlib.h>

using namespace std;

int main()
{
    long int i,j,k,lena,lenb,result[1000],carry,l,temp;
    char a[270],b[270];
    while(scanf("%s%s",&a,&b)==2)
    {
        lena=strlen(a);
        lenb=strlen(b);
        memset(result,0,sizeof(result));
        k=0;
        for(i=lenb-1;i>=0;i--)
        {
            k+=1;
            l=k-1;
            carry=0;
            for(j=lena-1;j>=0;j--)
            {
                l+=1;
                temp=(b[i]-48)*(a[j]-48)+carry+result[l];
                result[l]=temp%10;
                carry=temp/10;
            }
            if(carry>0)
            {
                l+=1;
                result[l]=carry;
            }

        }
        if(strcmp(a,"0")==0 ||strcmp(b,"0")==0 )
            printf("0");
        else
        {
            for(i=l;i>=1;i--)
                printf("%ld",result[i]);
        }

        printf("\n");
    }
    return 0;
}