longest repeating character replacement solution

Author: yhkee0404

longest-repeating-character-replacement/yhkee0404.kt

@@ -0,0 +1,35 @@
+class Solution {
+    fun characterReplacement(s: String, k: Int): Int {
+        val cnts = MutableList<Int>('Z'.code - 'A'.code + 1) {0}
+        val queue = PriorityQueue<List<Int>>() {a, b -> b.first() - a.first()}
+        queue.offer(listOf(0, -1))
+        var ans = 0
+        var i = 0
+        var j = 0
+        while (j != s.length) { // T(n) = S(n) = O(nlogn)
+            while (queue.size > 1) {
+                val u = queue.peek()
+                if (u.first() == cnts[u.last()]) {
+                    break
+                }
+                queue.poll()
+            }
+            while (j != s.length) {
+                val diff = j - i - queue.peek().first()
+                if (diff > k) {
+                    break
+                }
+                val d = s[j].code - 'A'.code
+                if (diff == k && queue.peek().first() != cnts[d]) {
+                    break
+                }
+                j++
+                queue.offer(listOf(++cnts[d], d)) // O(logn)
+            }
+            ans = maxOf(ans, j - i)
+            val d = s[i++].code - 'A'.code
+            queue.offer(listOf(--cnts[d], d)) // O(logn)
+        }
+        return ans
+    }
+}