738. Monotone Increasing Digits

Medium

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An integer has monotone increasing digits if and only if each pair of adjacent digits x and y satisfy x <= y.

Given an integer n, return the largest number that is less than or equal to n with monotone increasing digits.

Example 1:

Input: n = 10
Output: 9

Example 2:

Input: n = 1234
Output: 1234

Example 3:

Input: n = 332
Output: 299

Constraints:

• 0 <= n <= 109

class Solution:
    def monotoneIncreasingDigits(self, n: int) -> int:
        string = list(str(n))
        length = len(string)
        startpoint = length
        for index in range(length-1, 0, -1):
            # print('Index', index)
            if string[index-1] > string[index]:
                startpoint = index-1
                num = int(string[index-1])
                # print(num)
                string[index-1] = str(num-1)
        for index in range(startpoint+1, length):
            string[index] = '9'
        # print(string)
        return int(''.join(string))