PlusOne.java

/*
You are given a large integer represented as an integer array digits, where each digits[i] is the ith digit of the integer. The digits are ordered from most significant to least significant in left-to-right order. The large integer does not contain any leading 0's.

Increment the large integer by one and return the resulting array of digits.

Example 1:
  Input: digits = [1,2,3]
  Output: [1,2,4]
  Explanation: The array represents the integer 123.
    Incrementing by one gives 123 + 1 = 124.
    Thus, the result should be [1,2,4].

Example 2:
  Input: digits = [4,3,2,1]
  Output: [4,3,2,2]
  Explanation: The array represents the integer 4321.
    Incrementing by one gives 4321 + 1 = 4322.
    Thus, the result should be [4,3,2,2].

Example 3:
  Input: digits = [9]
  Output: [1,0]
  Explanation: The array represents the integer 9.
    Incrementing by one gives 9 + 1 = 10.
    Thus, the result should be [1,0].
 

Constraints:
  
  1 <= digits.length <= 100
  0 <= digits[i] <= 9
  digits does not contain any leading 0's.

Link: [https://leetcode.com/problems/plus-one]
*/

class Solution {
    public int[] plusOne(int[] digits) {
        int indexDistinctNine = -1;

        for(int i = digits.length - 1; i >= 0; i--){
            if( digits[i] != 9 ){
                indexDistinctNine = i;
                break;
            }
        }

        if( indexDistinctNine == -1 ){
            int [] newArray = new int[digits.length + 1];
            newArray[0] = 1;

            return newArray;
        } else {
            digits[indexDistinctNine] += 1;

            for(int i = indexDistinctNine + 1; i <= digits.length - 1; i++){
                digits[i] = 0;
            }

            return digits;
        }
    } 
}