題目：Multiply Strings

難度：dedium

問題描述：

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.
• Converting the input string to integer is NOT allowed.
• You should NOT use internal library such as BigInteger
  .

用陣列模擬乘法的計算過程。面對nums1*nums2，先計算所有的temp【i】=nums1*nums2【i】，然後將每個temp【i】左邊填上合適數量的0之後再相加即可。

返回時注意開頭的0要捨去。

具體程式碼如下：

public class Solution {
    public String multiply(String num1, String num2) {
        if(num1.equals("0")||num2.equals("0")) return "0";
		char[] str1=new char[num1.length()];
		char[] str2=new char[num2.length()];
		int[][] temp=new int[num2.length()][num1.length()+1];
		int i;
		String rs="";
		for(i=0;i=0;i--){
			for(int j=s[i].length-1;j>=0;j--){
				temp[i][(len--)-(s.length-i)]=s[i][j];
			}
			len=temp[0].length;
		}
		for(int i=temp[0].length-1;i>=0;i--){
			sum=0;
			for(int j=0;j=0;i--){
			res[i+1]=(str[i]*m+jinwei)%10;
			jinwei=(str[i]*m+jinwei)/10;		
		}
		res[0]=jinwei;
		return res;
	}
}