feat: Add Solution to #243

Author: river20s

longest-repeating-character-replacement/river20s.py

@@ -0,0 +1,33 @@
+class Solution:
+    def characterReplacement(self, s: str, k: int) -> int:
+        # Time Complexity: O(n)
+        # Space Complexity: O(1)
+        n = len(s)
+        if n == 0:
+            return 0
+
+        left = 0
+        max_len = 0
+        char_counts = {} 
+        max_freq_count = 0 
+
+        for right in range(n):
+            right_char = s[right]
+            char_counts[right_char] = char_counts.get(right_char, 0) + 1
+            max_freq_count = max(max_freq_count, char_counts[right_char])
+            
+            current_window_length = right - left + 1
+            # 바꿔야 하는 문자 수 = 윈도우 길이 - 가장 많은 문자의 빈도수
+            changes_needed = current_window_length - max_freq_count
+            
+            # 만약 바꿔야 하는 문자 수가 k보다 크면 윈도우를 줄여야 함
+            if changes_needed > k:
+                left_char = s[left]
+                char_counts[left_char] -= 1
+                if char_counts[left_char] == 0: 
+                    del char_counts[left_char]
+                left += 1
+
+            max_len = max(max_len, right - left + 1) 
+
+        return max_len