longest repeating character replacement solution

Author: hyer0705

longest-repeating-character-replacement/hyer0705.ts

@@ -0,0 +1,22 @@
+function characterReplacement(s: string, k: number): number {
+  let longestLength = 0;
+  let windowStart = 0;
+
+  const countMap = new Map<string, number>();
+  let maxCount = 0;
+
+  for (let windowEnd = 0; windowEnd < s.length; windowEnd++) {
+    const currentCh = s[windowEnd];
+    countMap.set(currentCh, (countMap.get(currentCh) || 0) + 1);
+
+    maxCount = Math.max(maxCount, countMap.get(currentCh) || 0);
+    if (windowEnd - windowStart + 1 - maxCount > k) {
+      countMap.set(s[windowStart], (countMap.get(s[windowStart]) || 0) - 1);
+
+      windowStart++;
+    }
+    longestLength = Math.max(longestLength, windowEnd - windowStart + 1);
+  }
+
+  return longestLength;
+}