0738. Monotone Increasing Digits

https://leetcode.com/problems/monotone-increasing-digits

Description

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

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