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Plus One

Description​

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].

Code in Java

class Solution {
    public int[] plusOne(int[] digits) {
        int n = digits.length;

        for(int i=n-1; i>=0; --i) {
            ++digits[i];
            digits[i] = digits[i] % 10;
            if(digits[i] != 0) {
                return digits;
            }
        }
        digits = new int[n+1];
        digits[0] = 1;
        return digits;
    }
}