LeetCode Multiply Strings

Description

Given two numbers represented as strings, return multiplication of the numbers as a string.

Note: The numbers can be arbitrarily large and are non-negative.

The original problem is here.

The original code is here.

My Solution

I solve this problem in C++, as below:

/*
*Multiply Strings 
*Author: shuaijiang
*Email: zhaoshuaijiang8@gmail.com
*/
#include<iostream>
#include<math.h>
#include<vector>
#include<string>
#include<stdlib.h>
using namespace std;
 
class Solution {
public:
    string multiply(string num1, string num2) {
          int size1 = num1.size();
          int size2 = num2.size();
          vector<int> result(size1+size2,0);
          int k = size1+size2-2;
          for(int i=0;i<size1;i++){
              int n1 = num1[i]-'0';
              for(int j=0;j<size2;j++){
                  int n2 = num2[j]-'0';
                  result[k-i-j] += n1 * n2;
              }
          }
          int carries = 0;
        for(int i=0;i<size1+size2;i++){
            result[i] += carries;
            if(result[i] > 9){
                carries = result[i]/10;
                result[i] = result[i] % 10;
            }
            else
                carries = 0;
        }
        int i = size1+size2-1;
        while(result[i] == 0)
            i--;
        string str;
        for(int j=i;j>=0;j--){
            str.push_back(result[j]+'0');
        }
        if(str == "")
            str.push_back('0');
        return str;
    }
};

Note

To simplify the problem, reference to blog.