Plus One

66. Plus One

Given a non-negative integer represented as a non-empty array of digits, plus one to the integer.

You may assume the integer do not contain any leading zero, except the number 0 itself.

The digits are stored such that the most significant digit is at the head of the list.

public class Solution {
    public int[] plusOne(int[] digits) {
        if (digits == null || digits.length == 0) {
            return digits;
        }
        
        int carry = 1;
        
        for (int i = digits.length - 1; i >= 0; i--) {
            int num = digits[i] + carry;
            
            digits[i] = num % 10;
            carry = num / 10;
        }
        
        if (carry == 1) {
            int[] result = new int[digits.length + 1];
            result[0] = 1;
            
            for (int i = 1; i < result.length; i++) {
                result[i] = digits[i - 1];
            }
            
            return result;
        }
        
        return digits;
    }
}

Hope this helps,
Michael