leetcode--Multiply Strings

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.

[java] view plain copy

1. public class Solution {  
2.     public String multiply(String num1, String num2) {  
3.         int[] res = new int[num1.length()+num2.length()];  
4.         for(int i=num1.length()-1;i>=0;i--){           
5.             for(int j=num2.length()-1;j>=0;j--){  
6.                 int n1 = num1.charAt(i)-'0';  
7.                 int n2 = num2.charAt(j)-'0';  
8.                 res[i+j+1] += n1*n2;  
9.             }  
10.         }  
11.         int flag = 0;         
12.         for(int i=res.length-1;i>=0;i--){  
13.             int tmp = (res[i] + flag) % 10;  
14.             flag = (res[i] + flag) / 10;  
15.             res[i] = tmp;  
16.         }  
17.         StringBuilder sb = new StringBuilder();  
18.         for (int num : res) sb.append(num);  
19.         while (sb.length() != 0 && sb.charAt(0) == '0') sb.deleteCharAt(0);  
20.         return sb.length() == 0 ? "0" : sb.toString();  
21.     }  
22. }  

原文链接http://blog.csdn.net/crazy__chen/article/details/45752001