[tigermint] WEEK 08 Solutions

longest-repeating-character-replacement/tigermint.kt

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+/**
+TC: O(26n) = O(n)
+SC: O(26) = O(1)
+ */
+class Solution {
+    fun characterReplacement(s: String, k: Int): Int {
+        var left = 0
+        val charToCount = mutableMapOf<Char, Int>()
+        var maxFrequency = 0
+
+        for (right in s.indices) {
+            val added = s[right]
+            charToCount[added] = (charToCount[added] ?: 0) + 1
+
+            // 교체 횟수가 k를 넘으면 왼쪽을 당겨 윈도우 축소
+            while ((right - left + 1) - charToCount.values.max() > k) {
+                val removed = s[left]
+                charToCount[removed] = charToCount.getValue(removed) - 1
+                left++
+            }
+
+            maxFrequency = maxOf(maxFrequency, right - left + 1)
+        }
+
+        return maxFrequency
+    }
+}

reverse-bits/tigermint.kt

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+/**
+TC: O(32) = O(1)
+SC: O(1)
+ */
+class Solution {
+    fun reverseBits(n: Int): Int {
+        var result = 0
+        var num = n
+        repeat(32) {
+            result = (result shl 1) or (num and 1)
+            num = num ushr 1
+        }
+        return result
+    }
+}