PlusOne.java

//Given a non-empty array of digits representing a non-negative integer, plus one to the integer.
//
//The digits are stored such that the most significant digit is at the head of the list, and each element in the array contain a single digit.
//
//You may assume the integer does not contain any leading zero, except the number 0 itself.
//
//Example 1:
//
//Input: [1,2,3]
//Output: [1,2,4]
//Explanation: The array represents the integer 123.
//Example 2:
//
//Input: [4,3,2,1]
//Output: [4,3,2,2]
//Explanation: The array represents the integer 4321.

class Solution {
    public int[] plusOne(int[] digits) {
        for(int i = digits.length - 1; i >= 0; i--) {
            if(digits[i] < 9) {
                digits[i]++;
                return digits;
            }

            digits[i] = 0;
        }

        int[] result = new int[digits.length + 1];
        result[0] = 1;

        return result;
    }
}