- Longest Repeating Character Replacement DaleStudy#244

Author: ayosecu

longest-repeating-character-replacement/ayosecu.py

@@ -0,0 +1,37 @@
+class Solution:
+    """
+        - Time Complexity: O(n), n = len(s)
+        - Space Complexity: O(1)
+    """
+    def characterReplacement(self, s: str, k: int) -> int:      
+        cnt_arr = [0] * 26
+        max_cnt, max_len = 0, 0
+
+        # Two pointers: left/right
+        l = 0
+        for r in range(len(s)):
+            # Increase count and find max count by right pointer's alphabet
+            idx = ord(s[r]) - ord("A")
+            cnt_arr[idx] += 1
+            max_cnt = max(max_cnt, cnt_arr[idx])
+            
+            # Left pointer moves if changable characters exceed k
+            if (r - l + 1) - max_cnt > k:
+                idx = ord(s[l]) - ord("A")
+                cnt_arr[idx] -= 1
+                l += 1
+            
+            # Update the max length
+            max_len = max(max_len, r - l + 1)
+        
+        return max_len
+            
+tc = [
+        ("ABAB", 2, 4),
+        ("AABABBA", 1, 4)
+]
+
+sol = Solution()
+for i, (s, k, e) in enumerate(tc, 1):
+    r = sol.characterReplacement(s, k)
+    print(f"TC {i} is Passed!" if r == e else f"TC {i} is Failed! - Expected: {e}, Result: {r}")