add-strings

https://leetcode.com/problems/add-strings/

package com.company;

import java.util.LinkedList;
import java.util.List;
import java.util.Random;

public class Main {
    public String addStrings(String num1, String num2) {
        StringBuilder sb = new StringBuilder();
        if (num1.length() > num2.length()) {
            String tmp = num1;
            num1 = num2;
            num2 = tmp;
        }
        int i = num1.length() - 1;
        int j = num2.length() - 1;
        int carry = 0;
        int ival = 0;

        for (; i>=0 && j >= 0; i--,j--) {
            ival = carry + num1.charAt(i) - '0' + num2.charAt(j) - '0';
            if (ival > 9) {
                carry = ival / 10;
                ival %= 10;
            }
            else {
                carry = 0;
            }
            sb.append((char)('0' + ival));
        }

        // num2 is always longer than num1
        while (j >= 0) {
            ival = carry + num2.charAt(j) - '0';
            if (ival > 9) {
                carry = ival / 10;
                ival %= 10;
            }
            else {
                carry = 0;
            }
            sb.append((char)('0' + ival));
            j--;
        }

        // At first, it's missed
        if (carry > 0) {
            sb.append((char)('0' + carry));
        }

        return sb.reverse().toString();
    }

    public static void main(String[] args) {
        // write your code here
        System.out.println("Hello");

        String num1 = "1";
        String num2 = "9";
        Main obj = new Main();
        String ret = obj.addStrings(num1, num2);
        System.out.printf("ret: %s\n", ret);

    }
}