feat: add most frequent char v4

most-frequent-char/most_frequent_char_v4.py

@@ -0,0 +1,9 @@
+from collections import Counter
+
+def most_frequent_char(s):
+    tracker = Counter(s)
+    proxy = None
+    for char in s:
+        if proxy is None or tracker[char] > tracker[proxy]:
+            proxy = char
+    return proxy