PlusOne

Problem description

Given a non-negative number represented as an array of digits, plus one to the number. The digits are stored such that the most significant digit is at the head of the list.

• https://leetcode.com/problems/add-two-numbers/
• https://leetcode.com/problems/add-binary/
• https://leetcode.com/problems/plus-one/

Solution

public int[] plusOne(int[] digits) {
    int length = digits.length;
    digits[length - 1] = digits[length - 1] + 1;

    for (int i = length - 1; i > 0 && digits[i] == 10; i--) {
        digits[i] = 0;
        digits[i - 1] = digits[i - 1] + 1;
    }

    if (digits[0] == 10) {
        digits[0] = 0;
        int[] returnDigits = new int[length + 1];
        returnDigits[0] = 1;
        for (int i = 1; i < returnDigits.length; i++) {
            returnDigits[i] = digits[i-1];
        }
        return returnDigits;
    } else {
        return digits;
    }
}