Implemented Suffix Tree Data Structure (#11554)

* Implemented KD-Tree Data Structure

* Implemented KD-Tree Data Structure. updated DIRECTORY.md.

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* Create __init__.py

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* Replaced legacy `np.random.rand` call with `np.random.Generator` in kd_tree/example_usage.py

* Replaced legacy `np.random.rand` call with `np.random.Generator` in kd_tree/hypercube_points.py

* added typehints and docstrings

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* docstring for search()

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* Added tests. Updated docstrings/typehints

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* updated tests and used | for type annotations

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* E501 for build_kdtree.py, hypercube_points.py, nearest_neighbour_search.py

* I001 for example_usage.py and test_kdtree.py

* I001 for example_usage.py and test_kdtree.py

* Update data_structures/kd_tree/build_kdtree.py

Co-authored-by: Christian Clauss <cclauss@me.com>

* Update data_structures/kd_tree/example/hypercube_points.py

Co-authored-by: Christian Clauss <cclauss@me.com>

* Update data_structures/kd_tree/example/hypercube_points.py

Co-authored-by: Christian Clauss <cclauss@me.com>

* Added new test cases requested in Review. Refactored the test_build_kdtree() to include various checks.

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* Considered ruff errors

* Considered ruff errors

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* Update kd_node.py

* imported annotations from __future__

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* Implementation of the suffix tree data structure

* Adding data to DIRECTORY.md

* Minor file renaming

* minor correction

* renaming in DIRECTORY.md

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* Considering ruff part-1

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* Considering ruff part-5

* Implemented Suffix Tree Data Structure.
Added some comments to my files in #11532, #11554.

* updating DIRECTORY.md

* Implemented Suffix Tree Data Structure.
Added some comments to my files in #11532, #11554.

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Christian Clauss <cclauss@me.com>
Co-authored-by: Ramy-Badr-Ahmed <Ramy-Badr-Ahmed@users.noreply.github.com>

DIRECTORY.md

@@ -291,6 +291,13 @@
     * [Stack With Doubly Linked List](data_structures/stacks/stack_with_doubly_linked_list.py)
     * [Stack With Singly Linked List](data_structures/stacks/stack_with_singly_linked_list.py)
     * [Stock Span Problem](data_structures/stacks/stock_span_problem.py)
+  * Suffix Tree
+    * Example
+      * [Example Usage](data_structures/suffix_tree/example/example_usage.py)
+    * [Suffix Tree](data_structures/suffix_tree/suffix_tree.py)
+    * [Suffix Tree Node](data_structures/suffix_tree/suffix_tree_node.py)
+    * Tests
+      * [Test Suffix Tree](data_structures/suffix_tree/tests/test_suffix_tree.py)
   * Trie
     * [Radix Tree](data_structures/trie/radix_tree.py)
     * [Trie](data_structures/trie/trie.py)

data_structures/kd_tree/build_kdtree.py

@@ -1,3 +1,11 @@
+#  Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed)
+#  in Pull Request: #11532
+#  https://github.com/TheAlgorithms/Python/pull/11532
+#
+#  Please mention me (@Ramy-Badr-Ahmed) in any issue or pull request
+#  addressing bugs/corrections to this file.
+#  Thank you!
+
 from data_structures.kd_tree.kd_node import KDNode
 
 

data_structures/kd_tree/example/example_usage.py

@@ -1,3 +1,11 @@
+#  Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed)
+#  in Pull Request: #11532
+#  https://github.com/TheAlgorithms/Python/pull/11532
+#
+#  Please mention me (@Ramy-Badr-Ahmed) in any issue or pull request
+#  addressing bugs/corrections to this file.
+#  Thank you!
+
 import numpy as np
 
 from data_structures.kd_tree.build_kdtree import build_kdtree

data_structures/kd_tree/example/hypercube_points.py

@@ -1,3 +1,11 @@
+#  Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed)
+#  in Pull Request: #11532
+#  https://github.com/TheAlgorithms/Python/pull/11532
+#
+#  Please mention me (@Ramy-Badr-Ahmed) in any issue or pull request
+#  addressing bugs/corrections to this file.
+#  Thank you!
+
 import numpy as np
 
 

data_structures/kd_tree/kd_node.py

@@ -1,3 +1,11 @@
+#  Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed)
+#  in Pull Request: #11532
+#  https://github.com/TheAlgorithms/Python/pull/11532
+#
+#  Please mention me (@Ramy-Badr-Ahmed) in any issue or pull request
+#  addressing bugs/corrections to this file.
+#  Thank you!
+
 from __future__ import annotations
 
 

data_structures/kd_tree/nearest_neighbour_search.py

@@ -1,3 +1,11 @@
+#  Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed)
+#  in Pull Request: #11532
+#  https://github.com/TheAlgorithms/Python/pull/11532
+#
+#  Please mention me (@Ramy-Badr-Ahmed) in any issue or pull request
+#  addressing bugs/corrections to this file.
+#  Thank you!
+
 from data_structures.kd_tree.kd_node import KDNode
 
 

data_structures/kd_tree/tests/test_kdtree.py

@@ -1,3 +1,11 @@
+#  Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed)
+#  in Pull Request: #11532
+#  https://github.com/TheAlgorithms/Python/pull/11532
+#
+#  Please mention me (@Ramy-Badr-Ahmed) in any issue or pull request
+#  addressing bugs/corrections to this file.
+#  Thank you!
+
 import numpy as np
 import pytest
 

data_structures/suffix_tree/example/example_usage.py

@@ -0,0 +1,37 @@
+#  Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed)
+#  in Pull Request: #11554
+#  https://github.com/TheAlgorithms/Python/pull/11554
+#
+#  Please mention me (@Ramy-Badr-Ahmed) in any issue or pull request
+#  addressing bugs/corrections to this file.
+#  Thank you!
+
+from data_structures.suffix_tree.suffix_tree import SuffixTree
+
+
+def main() -> None:
+    """
+    Demonstrate the usage of the SuffixTree class.
+
+    - Initializes a SuffixTree with a predefined text.
+    - Defines a list of patterns to search for within the suffix tree.
+    - Searches for each pattern in the suffix tree.
+
+    Patterns tested:
+        - "ana" (found) --> True
+        - "ban" (found) --> True
+        - "na" (found) --> True
+        - "xyz" (not found) --> False
+        - "mon" (found) --> True
+    """
+    text = "monkey banana"
+    suffix_tree = SuffixTree(text)
+
+    patterns = ["ana", "ban", "na", "xyz", "mon"]
+    for pattern in patterns:
+        found = suffix_tree.search(pattern)
+        print(f"Pattern '{pattern}' found: {found}")
+
+
+if __name__ == "__main__":
+    main()

data_structures/suffix_tree/suffix_tree.py

@@ -0,0 +1,66 @@
+#  Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed)
+#  in Pull Request: #11554
+#  https://github.com/TheAlgorithms/Python/pull/11554
+#
+#  Please mention me (@Ramy-Badr-Ahmed) in any issue or pull request
+#  addressing bugs/corrections to this file.
+#  Thank you!
+
+from data_structures.suffix_tree.suffix_tree_node import SuffixTreeNode
+
+
+class SuffixTree:
+    def __init__(self, text: str) -> None:
+        """
+        Initializes the suffix tree with the given text.
+
+        Args:
+            text (str): The text for which the suffix tree is to be built.
+        """
+        self.text: str = text
+        self.root: SuffixTreeNode = SuffixTreeNode()
+        self.build_suffix_tree()
+
+    def build_suffix_tree(self) -> None:
+        """
+        Builds the suffix tree for the given text by adding all suffixes.
+        """
+        text = self.text
+        n = len(text)
+        for i in range(n):
+            suffix = text[i:]
+            self._add_suffix(suffix, i)
+
+    def _add_suffix(self, suffix: str, index: int) -> None:
+        """
+        Adds a suffix to the suffix tree.
+
+        Args:
+            suffix (str): The suffix to add.
+            index (int): The starting index of the suffix in the original text.
+        """
+        node = self.root
+        for char in suffix:
+            if char not in node.children:
+                node.children[char] = SuffixTreeNode()
+            node = node.children[char]
+        node.is_end_of_string = True
+        node.start = index
+        node.end = index + len(suffix) - 1
+
+    def search(self, pattern: str) -> bool:
+        """
+        Searches for a pattern in the suffix tree.
+
+        Args:
+            pattern (str): The pattern to search for.
+
+        Returns:
+            bool: True if the pattern is found, False otherwise.
+        """
+        node = self.root
+        for char in pattern:
+            if char not in node.children:
+                return False
+            node = node.children[char]
+        return True

data_structures/suffix_tree/suffix_tree_node.py

@@ -0,0 +1,36 @@
+#  Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed)
+#  in Pull Request: #11554
+#  https://github.com/TheAlgorithms/Python/pull/11554
+#
+#  Please mention me (@Ramy-Badr-Ahmed) in any issue or pull request
+#  addressing bugs/corrections to this file.
+#  Thank you!
+
+from __future__ import annotations
+
+
+class SuffixTreeNode:
+    def __init__(
+        self,
+        children: dict[str, SuffixTreeNode] | None = None,
+        is_end_of_string: bool = False,
+        start: int | None = None,
+        end: int | None = None,
+        suffix_link: SuffixTreeNode | None = None,
+    ) -> None:
+        """
+        Initializes a suffix tree node.
+
+        Parameters:
+            children (dict[str, SuffixTreeNode] | None): The children of this node.
+            is_end_of_string (bool): Indicates if this node represents
+                                     the end of a string.
+            start (int | None): The start index of the suffix in the text.
+            end (int | None): The end index of the suffix in the text.
+            suffix_link (SuffixTreeNode | None): Link to another suffix tree node.
+        """
+        self.children = children or {}
+        self.is_end_of_string = is_end_of_string
+        self.start = start
+        self.end = end
+        self.suffix_link = suffix_link

data_structures/suffix_tree/tests/test_suffix_tree.py

@@ -0,0 +1,59 @@
+#  Created by: Ramy-Badr-Ahmed (https://github.com/Ramy-Badr-Ahmed)
+#  in Pull Request: #11554
+#  https://github.com/TheAlgorithms/Python/pull/11554
+#
+#  Please mention me (@Ramy-Badr-Ahmed) in any issue or pull request
+#  addressing bugs/corrections to this file.
+#  Thank you!
+
+import unittest
+
+from data_structures.suffix_tree.suffix_tree import SuffixTree
+
+
+class TestSuffixTree(unittest.TestCase):
+    def setUp(self) -> None:
+        """Set up the initial conditions for each test."""
+        self.text = "banana"
+        self.suffix_tree = SuffixTree(self.text)
+
+    def test_search_existing_patterns(self) -> None:
+        """Test searching for patterns that exist in the suffix tree."""
+        patterns = ["ana", "ban", "na"]
+        for pattern in patterns:
+            with self.subTest(pattern=pattern):
+                assert self.suffix_tree.search(
+                    pattern
+                ), f"Pattern '{pattern}' should be found."
+
+    def test_search_non_existing_patterns(self) -> None:
+        """Test searching for patterns that do not exist in the suffix tree."""
+        patterns = ["xyz", "apple", "cat"]
+        for pattern in patterns:
+            with self.subTest(pattern=pattern):
+                assert not self.suffix_tree.search(
+                    pattern
+                ), f"Pattern '{pattern}' should not be found."
+
+    def test_search_empty_pattern(self) -> None:
+        """Test searching for an empty pattern."""
+        assert self.suffix_tree.search(""), "An empty pattern should be found."
+
+    def test_search_full_text(self) -> None:
+        """Test searching for the full text."""
+        assert self.suffix_tree.search(
+            self.text
+        ), "The full text should be found in the suffix tree."
+
+    def test_search_substrings(self) -> None:
+        """Test searching for substrings of the full text."""
+        substrings = ["ban", "ana", "a", "na"]
+        for substring in substrings:
+            with self.subTest(substring=substring):
+                assert self.suffix_tree.search(
+                    substring
+                ), f"Substring '{substring}' should be found."
+
+
+if __name__ == "__main__":
+    unittest.main()