Plus One

Given a non-empty array of decimal digits representing a non-negative integer, increment one to the integer. The digits are stored such that the most significant digit is at the head of the list, and each element in the array contains a single digit. You may assume the integer does not contain any leading zero, except the number 0 itself. Examples Input: [1,2,3] Output: [1,2,4] Explanation: The input represents the number 123. Input: [4,3,2,1] Output: [4,3,2,2] Explanation: The input represents the number 4321. Constraints The length of the array is within the range [1, 1000]. Example Input [1,2,3]