LeetCode Entry

Maximum 69 Number

7.11.2022 easy 2022 kotlin

The simplest implementations would be converting to array of digits, replacing the first and converting back.

https://leetcode.com/problems/maximum-69-number/ easy

    fun maximum69Number (num: Int): Int {
        var n = num
        if (6666 <= n && n <= 6999) return num + 3000
        if (n > 9000) n -= 9000
        if (666 <= n && n <= 699) return num + 300
        if (n > 900) n -= 900
        if (66 <= n && n <= 69) return num + 30
        if (n > 90) n -= 90
        if (6 == n) return num + 3
        return num
    }

Explanation: The simplest implementations would be converting to array of digits, replacing the first and converting back. However we can observe that numbers are in range 6-9999, so we can hardcode some logic.

Speed: O(1), Memory: O(1)