feat(strings, trie): is prefix of word

DIRECTORY.md

@@ -707,6 +707,8 @@
     * [Test Greatest Common Divisor](https://github.com/BrianLusina/PythonSnips/blob/master/pystrings/greatest_common_divisor/test_greatest_common_divisor.py)
   * Inttostr
     * [Test Int To Str](https://github.com/BrianLusina/PythonSnips/blob/master/pystrings/inttostr/test_int_to_str.py)
+  * Is Prefix
+    * [Test Is Prefix Of Word](https://github.com/BrianLusina/PythonSnips/blob/master/pystrings/is_prefix/test_is_prefix_of_word.py)
   * Is Unique
     * [Test Is Unique](https://github.com/BrianLusina/PythonSnips/blob/master/pystrings/is_unique/test_is_unique.py)
   * Issubsequence

algorithms/fast_and_slow/happy_number/README.md

@@ -15,26 +15,26 @@ Return TRUE if n is a happy number, and FALSE if not.
 
 ### Sample Example 1
 
-![Sample Example 1.1](example_1_1.png)
-![Sample Example 1.2](example_1_2.png)
-![Sample Example 1.3](example_1_3.png)
+![Sample Example 1.1](images/example/example_1_1.png)
+![Sample Example 1.2](images/example/example_1_2.png)
+![Sample Example 1.3](images/example/example_1_3.png)
 
 ### Sample Example 2
 
-![Sample Example 2.1](example_2_1.png)
-![Sample Example 2.2](example_2_2.png)
-![Sample Example 2.3](example_2_3.png)
+![Sample Example 2.1](images/example/example_2_1.png)
+![Sample Example 2.2](images/example/example_2_2.png)
+![Sample Example 2.3](images/example/example_2_3.png)
 
 ## Solution Example
 
 Below shows an example using Floyd's Cycle Detection Algorithm or Tortoise and Hare algorithm to detect a cycle
 for the number 2.
 
-![Solution Example 1](solution_example_1.png)
-![Solution Example 2](solution_example_2.png)
-![Solution Example 3](solution_example_3.png)
-![Solution Example 4](solution_example_4.png)
-![Solution Example 5](solution_example_5.png)
-![Solution Example 6](solution_example_6.png)
-![Solution Example 7](solution_example_7.png)
-![Solution Example 8](solution_example_8.png)
+![Solution Example 1](images/solution/solution_example_1.png)
+![Solution Example 2](images/solution/solution_example_2.png)
+![Solution Example 3](images/solution/solution_example_3.png)
+![Solution Example 4](images/solution/solution_example_4.png)
+![Solution Example 5](images/solution/solution_example_5.png)
+![Solution Example 6](images/solution/solution_example_6.png)
+![Solution Example 7](images/solution/solution_example_7.png)
+![Solution Example 8](images/solution/solution_example_8.png)

algorithms/fast_and_slow/happy_number/test_happy_number.py

@@ -113,6 +113,12 @@ def test_9(self):
         actual = is_happy_number_2(number)
         self.assertFalse(actual)
 
+    def test_10(self):
+        """should return false for 20"""
+        number = 20
+        actual = is_happy_number_2(number)
+        self.assertFalse(actual)
+
 
 if __name__ == "__main__":
     unittest.main()

datastructures/streams/stream_checker/__init__.py

@@ -58,7 +58,7 @@ def query(self, letter: str) -> bool:
 
         # Iterate stream in reverse (newest character first)
         for character in reversed(self.stream):
-            # Check for dead end (critical for query logic)
+            # Check for dead-end (critical for query logic)
             if character not in current.children:
                 return False
 

datastructures/trees/trie/trie.py

@@ -1,30 +1,59 @@
-from typing import List
+from typing import List, Optional
 from datastructures.trees.trie.trie_node import TrieNode
 
 
 class Trie:
     def __init__(self):
         self.root = TrieNode()
 
-    def insert(self, word: str) -> None:
+    def insert(self, word: str, index: Optional[int] = None) -> None:
+        """
+        Inserts a word into the Trie. This has an optional index argument that allows
+        us to track the index of the word in the original list. So, if inserting words from a list such as "The author
+        is smart", the index of "smart" would be 3. If this is not provided, i.e. None, then each node in the tree will
+        have an index of None. Note that for each character in the word, we update the index of the node to the index of
+        the word. For example:
+
+        sentence = "please playground player"
+
+        Insert "please" (index 0):
+            p(0) → l(0) → e(0) → a(0) → s(0) → e(0)
+
+        Insert "playground" (index 1):
+        p(0) → l(0) → a(1) → y(1) → g(1) → ...
+                 ↘
+                  e(0) → a(0) → s(0) → e(0)
+
+        Insert "player" (index 2):
+        p(0) → l(0) → a(1) → y(1) → ...
+                              ↘
+                               e(2) → r(2)
+
+        Index then tracks the earliest index of the word in the original list. So, for the example above, the index of
+        "player" would be 2, not 0.
+
+        Parameters:
+            word (str): The word to insert
+            index (Optional[int]): The index of the word (default is None)
+
+        Returns:
+            None
+        """
         curr = self.root
 
         for char in word:
-            if char in curr.children:
-                curr = curr.children[char]
-            else:
-                new_node = TrieNode()
-                curr.children[char] = new_node
-                curr = new_node
+            curr = curr.children[char]
+            if index is not None:
+                curr.index = min(curr.index or float("inf"), index)
 
         curr.is_end = True
 
     def search(self, word: str) -> List[str]:
-        curr = self.root
-
         if len(word) == 0:
             return []
 
+        curr = self.root
+
         for char in word:
             if char in curr.children:
                 curr = curr.children[char]
@@ -35,10 +64,10 @@ def search(self, word: str) -> List[str]:
 
         def dfs(node: TrieNode, prefix: str) -> None:
             if node.is_end:
-                output.append((prefix + node.char))
+                output.append((prefix + "".join(node.children.keys())))
 
             for child in node.children.values():
-                dfs(child, prefix + node.char)
+                dfs(child, prefix + "".join(node.children.keys()))
 
         dfs(curr, word[:-1])
         return output
@@ -55,3 +84,6 @@ def starts_with(self, prefix: str) -> bool:
             curr = curr.children[char]
 
         return True
+
+    def __repr__(self):
+        return f"Trie(root={self.root})"

datastructures/trees/trie/trie_node.py

@@ -1,4 +1,4 @@
-from typing import DefaultDict
+from typing import DefaultDict, Optional
 from collections import defaultdict
 
 
@@ -18,6 +18,45 @@ def __init__(self):
         """
         self.children: DefaultDict[str, TrieNode] = defaultdict(TrieNode)
         self.is_end = False
+        self.index: Optional[int] = None
 
     def __repr__(self):
-        return f"TrieNode({self.children.items()}, {self.is_end})"
+        return f"TrieNode(children={self.children.items()}, index={self.index}, is_end={self.is_end})"
+
+    def insert(self, word: str, index: int):
+        """
+        Inserts a word into the TrieNode.
+
+        Parameters:
+            word (str): The word to insert
+            index (int): The index of the word
+
+        Returns:
+            None
+        """
+        curr = self
+        for char in word:
+            curr = curr.children[char]
+            curr.index = min(curr.index or float("inf"), index)
+        curr.is_end = True
+
+    def search_prefix(self, prefix: str) -> int:
+        """
+        Searches for a prefix in the TrieNode.
+
+        Parameters:
+            prefix (str): The prefix to search for
+
+        Returns:
+            int: The index of the word if the prefix is found, -1 otherwise
+        """
+        current = self
+
+        for char in prefix:
+            if char not in current.children:
+                return -1
+
+            # Traverse to the next node
+            current = current.children[char]
+
+        return current.index if current.index is not None else -1

pystrings/is_prefix/README.md

@@ -0,0 +1,24 @@
+# Check if a Word is a Prefix of Any Word in a Sentence
+
+You are given a sentence containing words separated by single spaces and a searchWord. Your task is to determine whether 
+searchWord is a prefix of any word in the sentence.
+Return the 1-based index of the first word in which searchWord appears as a prefix.
+
+- If searchWord is a prefix of multiple words, return the index of the earliest such word. 
+- If no word starts with searchWord, return −1
+
+> A prefix of a string is any contiguous substring that begins at the first character.
+
+Constraints:
+
+- 1 <= sentence.length <= 100
+- 1 <= search_word.length <= 10 
+- The sentence consists of lowercase English letters and spaces. 
+- search_word consists of lowercase English letters.
+
+## Examples
+
+![Example 1](./images/examples/is_prefix_example_1.png)
+![Example 2](./images/examples/is_prefix_example_2.png)
+![Example 3](./images/examples/is_prefix_example_3.png)
+![Example 4](./images/examples/is_prefix_example_4.png)

pystrings/is_prefix/__init__.py

@@ -0,0 +1,23 @@
+from datastructures.trees.trie.trie_node import TrieNode
+
+
+def is_prefix_of_word(sentence: str, search_word: str) -> int:
+    """
+    This function will check if a given search_word is a prefix of any word in a sentence.
+
+    Parameters:
+        sentence (str): The sentence to search in.
+        search_word (str): The prefix to search for.
+
+    Returns:
+        int: The index of the word if the prefix is found, -1 otherwise.
+    """
+    trie = TrieNode()
+    word_list = sentence.split(" ")
+
+    # Insert the words into the trie with their respective index
+    for index, word in enumerate(word_list, start=1):
+        trie.insert(word, index)
+
+    # Search for the prefix in the trie
+    return trie.search_prefix(search_word)

pystrings/is_prefix/test_is_prefix_of_word.py

@@ -0,0 +1,57 @@
+import unittest
+from . import is_prefix_of_word
+
+
+class IsPrefixOfWordTestCase(unittest.TestCase):
+    def test_1(self):
+        sentence = "i love coding"
+        search_word = "lov"
+        expected = 2
+        actual = is_prefix_of_word(sentence, search_word)
+        self.assertEqual(expected, actual)
+
+    def test_2(self):
+        sentence = "hello world"
+        search_word = "he"
+        expected = 1
+        actual = is_prefix_of_word(sentence, search_word)
+        self.assertEqual(expected, actual)
+
+    def test_3(self):
+        sentence = "please playground player"
+        search_word = "pla"
+        expected = 2
+        actual = is_prefix_of_word(sentence, search_word)
+        self.assertEqual(expected, actual)
+
+    def test_4(self):
+        sentence = "open source ai"
+        search_word = "deep"
+        expected = -1
+        actual = is_prefix_of_word(sentence, search_word)
+        self.assertEqual(expected, actual)
+
+    def test_5(self):
+        sentence = "cats dog cattle category"
+        search_word = "cat"
+        expected = 1
+        actual = is_prefix_of_word(sentence, search_word)
+        self.assertEqual(expected, actual)
+
+    def test_6(self):
+        sentence = "this is fine"
+        search_word = "fi"
+        expected = 3
+        actual = is_prefix_of_word(sentence, search_word)
+        self.assertEqual(expected, actual)
+
+    def test_7(self):
+        sentence = "hello world"
+        search_word = "x"
+        expected = -1
+        actual = is_prefix_of_word(sentence, search_word)
+        self.assertEqual(expected, actual)
+
+
+if __name__ == '__main__':
+    unittest.main()