solve longest repeating character replacement

Author: sora0319

longest-repeating-character-replacement/sora0319.java

@@ -0,0 +1,29 @@
+import java.util.HashMap;
+import java.util.Map;
+
+public class Solution {
+    public int characterReplacement(String s, int k) {
+        int maxLen = 0;
+        int maxCount = 0;
+        Map<Character, Integer> counter = new HashMap<>();
+        int start = 0;
+
+        for (int end = 0; end < s.length(); end++) {
+            char endChar = s.charAt(end);
+            counter.put(endChar, counter.getOrDefault(endChar, 0) + 1);
+            maxCount = Math.max(maxCount, counter.get(endChar));
+
+            while (end - start + 1 - maxCount > k) {
+                char startChar = s.charAt(start);
+                counter.put(startChar, counter.get(startChar) - 1);
+                start++;
+            }
+
+            maxLen = Math.max(maxLen, end - start + 1);
+        }
+
+        return maxLen;
+    }
+}
+
+