Longest Repeating Character with Replacement

longest_repeating_subsequence.kt

// This isn't the most optimal kotlin code. but it is one that solves all cases.


class Solution {
    fun characterReplacement(s: String, k: Int): Int {
        val n = s.length
        val maxCharMap = mutableMapOf<Char, Int>();
        var left = 0
        var maxCount = Float.NEGATIVE_INFINITY.toInt()
        var newMax = maxCount
        var maxLen = maxCount
        var char: Char? = null;
        var strLen: Int = 0
        var minCharFlip: Int = 0
        for (right in 0..n-1) {
            char = s[right]
            strLen = right.minus(left) + 1
            maxCharMap.put(char, maxCharMap.getOrDefault(char, 0) + 1)
            newMax = (
                maxOf(
                    maxCount, 
                    maxCharMap.getOrElse(char) { 0 } 
                )
            )
            
            minCharFlip = strLen.minus(newMax)
            when (minCharFlip > k) {
                true -> {
                    maxCharMap.put(
                        s[left], maxCharMap.getOrDefault(s[left], 0) - 1)
                    left++
                    strLen = right.minus(left).plus(1)
                    maxCharMap.forEach { (key, value) -> 
                        maxCount = maxOf(maxCount, value)
                    }
                }
                
                else -> maxCount = newMax
                
            }
            
            maxLen = maxOf(maxLen, strLen)
        }
        return maxLen
    }
}