Add hamming distance (#6194)

* Add hamming distance

* Fix doctest

* Refactor

* Raise ValueError when string lengths are different

strings/hamming_distance.py

@@ -0,0 +1,39 @@
+def hamming_distance(string1: str, string2: str) -> int:
+    """Calculate the Hamming distance between two equal length strings
+    In information theory, the Hamming distance between two strings of equal
+    length is the number of positions at which the corresponding symbols are
+    different. https://en.wikipedia.org/wiki/Hamming_distance
+
+    Args:
+        string1 (str): Sequence 1
+        string2 (str): Sequence 2
+
+    Returns:
+        int: Hamming distance
+
+    >>> hamming_distance("python", "python")
+    0
+    >>> hamming_distance("karolin", "kathrin")
+    3
+    >>> hamming_distance("00000", "11111")
+    5
+    >>> hamming_distance("karolin", "kath")
+    ValueError: String lengths must match!
+    """
+    if len(string1) != len(string2):
+        raise ValueError("String lengths must match!")
+
+    count = 0
+
+    for char1, char2 in zip(string1, string2):
+        if char1 != char2:
+            count += 1
+
+    return count
+
+
+if __name__ == "__main__":
+
+    import doctest
+
+    doctest.testmod()