Leetcode:multiply Strings

Problem:

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

Note:the numbers can be arbitrarily large and is non-negative.

Solution:

Multiply each bit of string 1 with string2. Be careful of the carryin and the position.

Code:

public class Solution {public String multiply (string num1, String num2) {if (NUM1 = null | | num2 = NULL) RE        Turn "";        Int[] result = new Int[num1.length () + num2.length ()];        int carryin = 0;            for (int i = Num1.length ()-1; I >= 0; i--) {carryin = 0;                for (int j = num2.length ()-1; J >= 0; j--) {int a = Num1.charat (i)-' 0 ';                int B = Num2.charat (j)-' 0 ';                int TMP = A * b + carryin + result[num1.length ()-1 + num2.length ()-1-i-J];                Carryin = TMP/10;            Result[num1.length ()-1 + num2.length ()-1-i-j] = tmp% 10;        } result[num1.length ()-1 + num2.length ()-1-i + 1] = Carryin;        }//Result[num1.length () + num2.length ()-1] = Carryin;        int i = num1.length () + num2.length ()-1;        while (I >= 1 && result[i] = = 0) {i--;        } String s = ""; for (int j = i; J >= 0;        j--) {s = s + result[j];    } return s; }}

Leetcode:multiply Strings