feat: add valid anagram algorithm in Strings folder

strings/valid_anagram.py

@@ -0,0 +1,53 @@
+"""
+Checks whether two strings are valid anagrams of each other.
+
+An anagram is a word formed by rearranging the letters of another word,
+using all the original letters exactly once.
+
+For example:
+listen → silent
+evil → live
+
+This can be done efficiently using Python's collections.Counter
+to compare character frequencies in both strings.
+
+Example:
+>>> is_anagram("listen", "silent")
+True
+>>> is_anagram("evil", "vile")
+True
+>>> is_anagram("hello", "bello")
+False
+>>> is_anagram("", "")
+True
+>>> is_anagram("a", "aa")
+False
+"""
+
+from collections import Counter
+
+
+def is_anagram(s1: str, s2: str) -> bool:
+    """
+    Returns True if the two input strings are anagrams of each other.
+
+    The comparison is case-sensitive and ignores no characters.
+
+    >>> is_anagram("listen", "silent")
+    True
+    >>> is_anagram("triangle", "integral")
+    True
+    >>> is_anagram("apple", "papel")
+    True
+    >>> is_anagram("rat", "car")
+    False
+    >>> is_anagram("a", "aa")
+    False
+    """
+    return Counter(s1) == Counter(s2)
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()