[Leetcode]66. Plus One

📄 Description

You are given a large integer represented as an integer array digits, where each digits[i] is the $i^{th}$ 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].

Constraints:

• 1 <= digits.length <= 100
• 0 <= digits[i] <= 9
• digits does not contain any leading 0's.

🔨 My Solution

1. digits 를 string(문자열)으로 convert 후 int(정수형)으로 convert
2. 더하기 1 연산 수행
3. list(리스트) 형태로 return

💻 My Submission

class Solution:
    def plusOne(self, digits: List[int]) -> List[int]:
        # convert it to string and then to integer
        num=int("".join([str(d) for d in digits]))
        string_num=str(num+1)
        
        return [n for n in string_num]

💭 Another approach

def plusOne(digits):
    num = 0
    for i in range(len(digits)):
    	num += digits[i] * pow(10, (len(digits)-1-i))
    return [int(i) for i in str(num+1)]

Reference

• https://leetcode.com/problems/plus-one/
• https://leetcode.com/problems/plus-one/discuss/24085/Simple-Python-solution-with-explanation-(Plus-One)