66. Plus One

Problem Statement

link: https://leetcode.com/problems/plus-one/ https://leetcode.cn/problems/plus-one/

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:

Input: digits = [1,2,3] Output: [1,2,4]

Input: digits = [4,3,2,1] Output: [4,3,2,2]

Input: digits = [9] Output: [1,0]

Solution Approach

Simulate the process of elementary addition starting from the least significant digit.

Algorithm

1. Iteration: Begin from the last digit, adding one.
2. Carry Management: If it becomes 10, set it to 0 and carry one to the previous digit.
3. Overflow: If all digits are 9, prepend a 1 to handle overflow.

Implement

    class Solution:
    def plusOne(self, digits: List[int]) -> List[int]:
      for i in range(len(digits)-1, -1, -1):
          if digits[i] == 9:
              digits[i] = 0
          else:
              digits[i] += 1
              return digitas
      return [1] + digits 

    
    

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