add solution: implement-trie-prefix-tree

Author: dusunax

implement-trie-prefix-tree/dusunax.py

@@ -0,0 +1,49 @@
+'''
+# 208. Implement Trie (Prefix Tree)
+
+```
+- Node structure
+{children: {char: {children: { ... }, is_end: False}}, is_end: False}
+```
+
+## Time and Space Complexity
+
+```
+TC: O(n)
+SC: O(n)
+```
+
+#### TC is O(n):
+- insert, search, startsWith: iterating through the word just once. = O(n)
+
+#### SC is O(n):
+- insert, search, startsWith: using a hash map to store the children nodes. = O(n)
+'''
+
+class Trie:
+    def __init__(self):
+        self.root = {"children": {}, "is_end": False}
+
+    def insert(self, word: str) -> None:
+        node = self.root
+        for char in word:
+            if char not in node["children"]:
+                node["children"][char] = {"children": {}, "is_end": False}
+            node = node["children"][char]
+        node["is_end"] = True
+
+    def search(self, word: str) -> bool:
+        node = self.root
+        for char in word:
+            if char not in node["children"]:
+                return False
+            node = node["children"][char]
+        return node["is_end"]
+
+    def startsWith(self, prefix: str) -> bool:
+        node = self.root
+        for char in prefix:
+            if char not in node["children"]:
+                return False
+            node = node["children"][char]
+        return True