feat: Enhance Trie with New Features

- Added `count_words()` to count the total number of words in the Trie.
- Implemented `longest_common_prefix()` to find the longest common prefix among all words.
- Added `autocomplete(prefix)` to provide autocomplete suggestions.
- Implemented `bulk_insert(words)` to insert multiple words at once.
- Added `clear()` method to remove all words from the Trie.
- Implemented `is_empty()` to check if the Trie is empty.
- Added `find_all_words()` to retrieve all stored words.
- Implemented `shortest_unique_prefix(word)` to find the shortest unique prefix of a word.
- Added `starts_with(prefix)` to check if any word starts with a given prefix.
- Implemented `longest_word()` to find the longest word in the Trie.

Author: asmit27rai

pydatastructs/strings/tests/test_trie.py

@@ -47,3 +47,38 @@ def test_Trie():
         for j in range(i + 1):
             assert trie_1.is_inserted(prefix_strings_1[j])
             assert trie_1.is_present(prefix_strings_1[j])
+
+    assert trie_1.count_words() == 3
+
+    assert trie_1.longest_common_prefix() == "dict"
+
+    assert trie_1.autocomplete("dict") == ["dict", "dicts", "dicts_lists_tuples"]
+
+    trie_2 = Trie()
+    trie_2.bulk_insert(["apple", "app", "apricot", "banana"])
+    assert trie_2.count_words() == 4
+
+    trie_2.clear()
+    assert trie_2.count_words() == 0
+    assert trie_2.is_empty()
+
+    assert trie_2.is_empty()
+
+    trie_3 = Trie()
+    trie_3.insert("hello")
+    trie_3.insert("world")
+    assert sorted(trie_3.all_words()) == ["hello", "world"]
+
+    trie_4 = Trie()
+    trie_4.bulk_insert(["zebra", "dog", "duck", "dove"])
+    print(trie_4.shortest_unique_prefix())
+    assert trie_4.shortest_unique_prefix() == {
+        "zebra": "z",
+        "dog": "dog",
+        "duck": "du",
+        "dove": "dov"
+    }
+    assert trie_4.starts_with("do")
+    assert not trie_4.starts_with("cat")
+
+    assert trie_4.longest_word() == "zebra"

pydatastructs/strings/trie.py

@@ -49,7 +49,10 @@ class Trie(object):
     @classmethod
     def methods(cls):
         return ['__new__', 'insert', 'is_present', 'delete',
-                'strings_with_prefix']
+                'strings_with_prefix', 'count_words', 'longest_common_prefix',
+                'autocomplete', 'bulk_insert', 'clear', 'is_empty',
+                'all_words', 'shortest_unique_prefix', 'starts_with',
+                'longest_word']
 
     def __new__(cls, **kwargs):
         raise_if_backend_is_not_python(
@@ -176,26 +179,191 @@ def strings_with_prefix(self, string: str) -> list:
             The list of strings with the given prefix.
         """
 
-        def _collect(prefix: str, node: TrieNode, strings: list) -> str:
-            TrieNode_stack = Stack()
-            TrieNode_stack.append((node, prefix))
-            while TrieNode_stack:
-                walk, curr_prefix = TrieNode_stack.pop()
-                if walk.is_terminal:
-                    strings.append(curr_prefix + walk.char)
-                for child in walk._children:
-                    TrieNode_stack.append((walk.get_child(child), curr_prefix + walk.char))
+        def _collect(node: TrieNode, prefix: str, strings: list):
+            if node.is_terminal:
+                strings.append(prefix)
+            for child in node._children:
+                _collect(node.get_child(child), prefix + child, strings)
 
         strings = []
-        prefix = ""
         walk = self.root
         for char in string:
-            walk = walk.get_child(char)
-            if walk is None:
+            if walk.get_child(char) is None:
                 return strings
-            prefix += char
-        if walk.is_terminal:
-            strings.append(walk.char)
-        for child in walk._children:
-            _collect(prefix, walk.get_child(child), strings)
+            walk = walk.get_child(char)
+        _collect(walk, string, strings)
         return strings
+
+    def count_words(self) -> int:
+        """
+        Returns the total number of words inserted into the trie.
+
+        Returns
+        =======
+
+        count: int
+            The total number of words in the trie.
+        """
+        def _count(node: TrieNode) -> int:
+            count = 0
+            if node.is_terminal:
+                count += 1
+            for child in node._children:
+                count += _count(node.get_child(child))
+            return count
+
+        return _count(self.root)
+
+    def longest_common_prefix(self) -> str:
+        """
+        Finds the longest common prefix among all the words in the trie.
+
+        Returns
+        =======
+
+        prefix: str
+            The longest common prefix.
+        """
+        prefix = ""
+        walk = self.root
+        while len(walk._children) == 1 and not walk.is_terminal:
+            char = next(iter(walk._children))
+            prefix += char
+            walk = walk.get_child(char)
+        return prefix
+
+    def autocomplete(self, prefix: str) -> list:
+        """
+        Provides autocomplete suggestions based on the given prefix.
+
+        Parameters
+        ==========
+
+        prefix: str
+
+        Returns
+        =======
+
+        suggestions: list
+            A list of autocomplete suggestions.
+        """
+        return self.strings_with_prefix(prefix)
+
+    def bulk_insert(self, words: list) -> None:
+        """
+        Inserts multiple words into the trie.
+
+        Parameters
+        ==========
+
+        words: list
+            A list of words to be inserted.
+
+        Returns
+        =======
+
+        None
+        """
+        for word in words:
+            self.insert(word)
+
+    def clear(self) -> None:
+        """
+        Clears the trie, removing all words.
+
+        Returns
+        =======
+
+        None
+        """
+        self.root = TrieNode()
+
+    def is_empty(self) -> bool:
+        """
+        Checks if the trie is empty.
+
+        Returns
+        =======
+
+        bool
+            True if the trie is empty, False otherwise.
+        """
+        return not self.root._children
+
+    def all_words(self) -> list:
+        """
+        Retrieves all words stored in the trie.
+
+        Returns
+        =======
+
+        words: list
+            A list of all words in the trie.
+        """
+        return self.strings_with_prefix("")
+
+    def shortest_unique_prefix(self) -> dict:
+        """
+        Finds the shortest unique prefix for each word in the trie.
+
+        Returns
+        =======
+        prefixes: dict
+            A dictionary where keys are words and values are their shortest unique prefixes.
+        """
+        def _find_prefix(node: TrieNode, prefix: str, prefixes: dict, word: str = ""):
+            if node.is_terminal:
+                prefixes[word] = prefix  # Store full word as key
+            for child in node._children:
+                new_word = word + child  # Build full word
+                new_prefix = prefix + child
+                if len(node._children) > 1 or node.is_terminal:
+                    _find_prefix(node.get_child(child), new_prefix, prefixes, new_word)
+                else:
+                    _find_prefix(node.get_child(child), prefix, prefixes, new_word)
+
+        prefixes = {}
+        _find_prefix(self.root, "", prefixes)
+        return prefixes
+
+
+    def starts_with(self, prefix: str) -> bool:
+        """
+        Checks if any word in the trie starts with the given prefix.
+
+        Parameters
+        ==========
+
+        prefix: str
+
+        Returns
+        =======
+
+        bool
+            True if any word starts with the prefix, False otherwise.
+        """
+        walk = self.root
+        for char in prefix:
+            if walk.get_child(char) is None:
+                return False
+            walk = walk.get_child(char)
+        return True
+
+    def longest_word(self) -> str:
+        """
+        Finds the longest word stored in the trie.
+
+        Returns
+        =======
+
+        word: str
+            The longest word in the trie.
+        """
+        def _longest(node: TrieNode, current_word: str, longest_word: str) -> str:
+            if node.is_terminal and len(current_word) > len(longest_word):
+                longest_word = current_word
+            for child in node._children:
+                longest_word = _longest(node.get_child(child), current_word + child, longest_word)
+            return longest_word
+
+        return _longest(self.root, "", "")