Add longest-repeating-character-replacement solution in TS

Author: Jeehay28

longest-repeating-character-replacement/Jeehay28.ts

@@ -0,0 +1,27 @@
+// TC: O(n)
+// SC: O(1)
+function characterReplacement(s: string, k: number): number {
+  const freqMap = new Map<string, number>();
+  let left = 0;
+  let maxFreqCnt = 0;
+  let result = 0;
+
+  for (let right = 0; right < s.length; right++) {
+    const ch = s[right];
+    freqMap.set(ch, (freqMap.get(ch)! | 0) + 1);
+    maxFreqCnt = Math.max(maxFreqCnt, freqMap.get(ch)!);
+
+    while (right - left + 1 - maxFreqCnt > k) {
+      // Shrink the sliding window by moving the left pointer to the right.
+      // As we move left, decrease the frequency count of the character being excluded from the window.
+      const ch = s[left];
+      freqMap.set(ch, freqMap.get(ch)! - 1);
+      left++;
+    }
+
+    result = Math.max(result, right - left + 1);
+  }
+
+  return result;
+}
+