Fixes The Bug In Radix Tree. Issue #11316

data_structures/trie/radix_tree.py

@@ -1,9 +1,11 @@
 """
 A Radix Tree is a data structure that represents a space-optimized
-trie (prefix tree) in whicheach node that is the only child is merged
+trie (prefix tree) in which each node that is the only child is merged
 with its parent [https://en.wikipedia.org/wiki/Radix_tree]
 """
 
+import unittest
+
 
 class RadixNode:
     def __init__(self, prefix: str = "", is_leaf: bool = False) -> None:
@@ -62,6 +64,11 @@ def insert(self, word: str) -> None:
         -- A   (leaf)
         --- A   (leaf)
         """
+        ## Handle the Case where the word is empty by using an if branch
+        if word == "":
+            self.is_leaf = True
+            return
+
         # Case 1: If the word is the prefix of the node
         # Solution: We set the current node as leaf
         if self.prefix == word and not self.is_leaf:
@@ -80,11 +87,11 @@ def insert(self, word: str) -> None:
             )
 
             # Case 3: The node prefix is equal to the matching
-            # Solution: We insert remaining word on the next node
+            # Solution: We insert the remaining word on the next node
             if remaining_prefix == "":
                 self.nodes[matching_string[0]].insert(remaining_word)
 
-            # Case 4: The word is greater equal to the matching
+            # Case 4: The word is greater than or equal to the matching
             # Solution: Create a node in between both nodes, change
             # prefixes and add the new node for the remaining word
             else:
@@ -100,7 +107,7 @@ def insert(self, word: str) -> None:
                     self.nodes[matching_string[0]].insert(remaining_word)
 
     def find(self, word: str) -> bool:
-        """Returns if the word is on the tree
+        """Returns whether the word is on the tree
 
         Args:
             word (str): word to check
@@ -191,7 +198,7 @@ def print_tree(self, height: int = 0) -> None:
             value.print_tree(height + 1)
 
 
-def test_trie() -> bool:
+def test_trie() -> None:
     words = "banana bananas bandana band apple all beast".split()
     root = RadixNode()
     root.insert_many(words)
@@ -205,25 +212,41 @@ def test_trie() -> bool:
     assert not root.find("banana")
     assert root.find("bananas")
 
-    return True
 
+class TestRadixNode(unittest.TestCase):
+    def test_trie(self) -> None:
+        words = "banana bananas bandana band apple all beast".split()
+        root = RadixNode()
+        root.insert_many(words)
 
-def pytests() -> None:
-    assert test_trie()
+        assert all(root.find(word) for word in words)
+        assert not root.find("bandanas")
+        assert not root.find("apps")
+        root.delete("all")
+        assert not root.find("all")
+        root.delete("banana")
+        assert not root.find("banana")
+        assert root.find("bananas")
 
+    def test_trie_2(self) -> None:
+        """
+        Now add a new test case that inserts
+        foobbb, fooaaa, foo in the given order and checks
+        for different assertions
+        """
+        words = "foobbb fooaaa foo".split()
+        root = RadixNode()
+        root.insert_many(words)
 
-def main() -> None:
-    """
-    >>> pytests()
-    """
-    root = RadixNode()
-    words = "banana bananas bandanas bandana band apple all beast".split()
-    root.insert_many(words)
-
-    print("Words:", words)
-    print("Tree:")
-    root.print_tree()
+        assert all(root.find(word) for word in words)
+        root.delete("foo")
+        assert not root.find("foo")
+        assert root.find("foobbb")
+        assert root.find("fooaaa")
 
 
 if __name__ == "__main__":
-    main()
+    import doctest
+
+    doctest.testmod()
+    unittest.main()