Merge pull request #240 from sailok/master

Adding Leetcode Problem 208. Implement Trie

Author: larissalages

leetcode/python/Trie/Implement_Trie.py

@@ -0,0 +1,70 @@
+# Implement a trie with insert, search, and startsWith methods.
+
+# Example:
+
+# Trie trie = new Trie();
+# trie.insert("apple");
+# trie.search("apple");   // returns true
+# trie.search("app");     // returns false
+# trie.startsWith("app"); // returns true
+# trie.insert("app");   
+# trie.search("app");     // returns true
+
+class TrieNode:        
+    def __init__(self, val):
+        self.val = val
+        self.isEnd = False
+        self.children = [None for i in range(26)]
+class Trie:
+    def __init__(self):
+        """
+        Initialize your data structure here.
+        """
+        self.root = TrieNode('*')
+
+
+    def insert(self, word: str) -> None:
+        """
+        Inserts a word into the trie.
+        """
+        node = self.root
+        for c in word:
+            x = ord(c) - ord('a')
+            if node.children[x] is None:
+                node.children[x] = TrieNode(c)
+            node = node.children[x]
+        node.isEnd = True
+
+    def search(self, word: str) -> bool:
+        """
+        Returns if the word is in the trie.
+        """
+        node = self.root
+        for c in word:
+            x = ord(c) - ord('a')
+            if node.children[x] is not None:
+                node = node.children[x]
+            else:
+                return False
+        return node.isEnd
+
+
+    def startsWith(self, prefix: str) -> bool:
+        """
+        Returns if there is any word in the trie that starts with the given prefix.
+        """
+        node = self.root
+        for c in prefix:
+            x = ord(c) - ord('a')
+            if node.children[x] is not None:
+                node = node.children[x]
+            else:
+                return False
+        return True
+
+
+# Your Trie object will be instantiated and called as such:
+# obj = Trie()
+# obj.insert(word)
+# param_2 = obj.search(word)
+# param_3 = obj.startsWith(prefix)