fix: 简化代码

Author: lucifer

problems/424.longest-repeating-character-replacement.md

@@ -112,9 +112,8 @@ class Solution:
         for j in range(len(s)):
             counts[ord(s[j]) - ord("A")] += 1
             most_fraq = max(most_fraq, counts[ord(s[j]) - ord("A")])
-            while i < j and j - i + 1 - most_fraq > k:
+            if i < j and j - i + 1 - most_fraq > k:
                 counts[ord(s[i]) - ord("A")] -= 1
-                most_fraq = max(most_fraq, counts[ord(s[j]) - ord("A")])
                 i += 1
         return j - i + 1
 ```