add alternative_string_arrange method (#4595)

* add alternative_string_arrange method

* fix issue

* fix one more issue

* changed the variable name li to output_list

strings/alternative_string_arrange.py

@@ -0,0 +1,31 @@
+def alternative_string_arrange(first_str: str, second_str: str) -> str:
+    """
+    Return the alternative arrangements of the two strings.
+    :param first_str:
+    :param second_str:
+    :return: String
+    >>> alternative_string_arrange("ABCD", "XY")
+    'AXBYCD'
+    >>> alternative_string_arrange("XY", "ABCD")
+    'XAYBCD'
+    >>> alternative_string_arrange("AB", "XYZ")
+    'AXBYZ'
+    >>> alternative_string_arrange("ABC", "")
+    'ABC'
+    """
+    first_str_length: int = len(first_str)
+    second_str_length: int = len(second_str)
+    abs_length: int = (
+        first_str_length if first_str_length > second_str_length else second_str_length
+    )
+    output_list: list = []
+    for char_count in range(abs_length):
+        if char_count < first_str_length:
+            output_list.append(first_str[char_count])
+        if char_count < second_str_length:
+            output_list.append(second_str[char_count])
+    return "".join(output_list)
+
+
+if __name__ == "__main__":
+    print(alternative_string_arrange("AB", "XYZ"), end=" ")