feat(sliding_window): Add max sum subarray algorithm

Also updates DIRECTORY.md to include the new algorithm.

Author: Mayank29903

DIRECTORY.md

@@ -1258,6 +1258,9 @@
   * [Tabu Search](searches/tabu_search.py)
   * [Ternary Search](searches/ternary_search.py)
 
+  ## Sliding Window
+  * [Maximum Sum Subarray](sliding_window/maximum_sum_subarray.py)
+
 ## Sorts
   * [Bead Sort](sorts/bead_sort.py)
   * [Binary Insertion Sort](sorts/binary_insertion_sort.py)

sliding_window/maximum_sum_subarray.py

@@ -0,0 +1,61 @@
+# created by Mayank
+
+"""
+Sliding Window Algorithm: Longest Substring Without Repeating Characters
+https://en.wikipedia.org/wiki/Sliding_window
+
+This algorithm finds the length of the longest substring within a given string
+that does not contain any repeating characters. It uses a "sliding window"
+approach with two pointers to efficiently track the current substring.
+
+Complexity: O(n) where n is the length of the string.
+
+For doctests run following command:
+python3 -m doctest -v longest_substring_without_repeating_characters.py
+"""
+
+
+def longest_substring_without_repeating_characters(s: str) -> int:
+    """
+    Finds the length of the longest substring without repeating characters.
+
+    :param s: The input string.
+    :return: The length of the longest substring.
+
+    Examples:
+    >>> longest_substring_without_repeating_characters("abcabcbb")
+    3
+    >>> longest_substring_without_repeating_characters("bbbbb")
+    1
+    >>> longest_substring_without_repeating_characters("pwwkew")
+    3
+    >>> longest_substring_without_repeating_characters("")
+    0
+    >>> longest_substring_without_repeating_characters("abcdef")
+    6
+    >>> longest_substring_without_repeating_characters("tmmzuxt")
+    5
+    """
+    char_set = set()
+    left_pointer = 0
+    max_length = 0
+
+    for right_pointer in range(len(s)):
+        # If the character is already in the set, shrink the window from the left
+        while s[right_pointer] in char_set:
+            char_set.remove(s[left_pointer])
+            left_pointer += 1
+
+        # Add the new character to the set (expanding the window)
+        char_set.add(s[right_pointer])
+
+        # Update the maximum length found so far
+        max_length = max(max_length, right_pointer - left_pointer + 1)
+
+    return max_length
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()