leetcode 82: Multiply String

Multiply StringsMar 12 '12

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.

uncompleted

 

 

public class Solution {    public String multiply(String num1, String num2) {        // Start typing your Java solution below        // DO NOT write main() function        int sz1 = num1.length();        int sz2 = num2.length();                if(sz1<1 || sz2<1) return new String();                        char[] res = new char[sz1+sz2];                int  carry =0;        for(int i=sz1-1; i>=0; i--) {            char c = num1.charAt(i);            carry =0;            int k=i+sz2;                        for(int j=sz2-1; j>=0; j--) {                int t = (c-'0') * (num2.charAt(j)-'0') + carry;                if(res[k]!=0) t += res[k]-'0';                carry = t/10;                res[k--] = (char)(t%10 + '0');            }            if(carry!=0)             res[k] = (char)(carry + '0');        }                if(carry!=0) {            res[0] = (char)(carry + '0');            return new String(res);        } else {                         return new String(res,1,res.length-1);        }    }}