Plus One

use stack

public class Solution {
    public int[] plusOne(int[] digits) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        if(digits == null)
            return null;
        Stack<Integer> mystack = new Stack<Integer>();
        int carry = 1;
        int tmp = 0;
        for(int i = digits.length-1; i >= 0; i--)
        {
            tmp = digits[i] + carry;
            carry = tmp / 10;
            mystack.push(tmp%10);   
        }
        if(carry > 0)
            mystack.push(1);
        int[] result = new int[mystack.size()];
        for(int i = 0; i < result.length;i++)
            result[i] = mystack.pop();
        return result; 
    }
}