lc-66

//You are given a large integer represented as an integer array digits, where ea
//ch digits[i] is the ith digit of the integer. The digits are ordered from most s
//ignificant to least significant in left-to-right order. The large integer does n
//ot 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. 
// 
// Related Topics Array Math 
// 👍 4783 👎 4316


//leetcode submit region begin(Prohibit modification and deletion)
class Solution {
    public int[] plusOne(int[] digits) {
        if (digits == null || digits.length == 0) {
            return digits;
        }

        boolean all9 = true;

        for (int digit : digits) {
            if (digit != 9) {
                all9 = false;
                break;
            }
        }

        if (all9) {
            int[] result = new int[digits.length + 1];

            result[0] = 1;

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

            return result;
        } else {
            boolean carry = true;
            int i = digits.length - 1;
            while (carry) {
                digits[i] = digits[i] + 1;

                if (digits[i] == 10) {
                    digits[i] = 0;
                } else {
                    carry = false;
                }
                i--;
            }

            return digits;
        }
    }
}
//leetcode submit region end(Prohibit modification and deletion)