solve problem Implement Trie Prefix Tree

Author: P-ppc

README.md

@@ -236,6 +236,7 @@ All solutions will be accepted!
 |106|[Construct Binary Tree From Inorder And Postorder Traversal](https://leetcode-cn.com/problems/construct-binary-tree-from-inorder-and-postorder-traversal/description/)|[java/py/js](./algorithms/ConstructBinaryTreeFromInorderAndPostorderTraversal)|Medium|
 |105|[Construct Binary Tree From Preorder And Inorder Traversal](https://leetcode-cn.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/description/)|[java/py/js](./algorithms/ConstructBinaryTreeFromPreorderAndInorderTraversal)|Medium|
 |654|[Maximum Binary Tree](https://leetcode-cn.com/problems/maximum-binary-tree/description/)|[java/py/js](./algorithms/MaximumBinaryTree)|Medium|
+|208|[Implement Trie Prefix Tree](https://leetcode-cn.com/problems/implement-trie-prefix-tree/description/)|[java/py/js](./algorithms/ImplementTriePrefixTree)|Medium|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/ImplementTriePrefixTree/README.md

@@ -0,0 +1,2 @@
+# Implement Trie Prefix Tree
+This problem is easy to solve

algorithms/ImplementTriePrefixTree/Solution.java

@@ -0,0 +1,66 @@
+class Trie {
+    private class TrieNode {
+        public TrieNode[] children;
+        public Character ch;
+        public boolean isEnd;
+        
+        public TrieNode(Character ch) {
+            children = new TrieNode[26];
+            this.ch = ch;
+            this.isEnd = false;
+        }
+    }
+    
+    TrieNode root;
+    /** Initialize your data structure here. */
+    public Trie() {
+        root = new TrieNode(null);
+    }
+    
+    /** Inserts a word into the trie. */
+    public void insert(String word) {
+        TrieNode node = root;
+        for (char ch : word.toCharArray()) {
+            int index = (int) ch - 97;
+            if (node.children[index] == null) {
+                node.children[index] = new TrieNode(ch);
+            }
+            node = node.children[index];
+        }
+        node.isEnd = true;
+    }
+    
+    /** Returns if the word is in the trie. */
+    public boolean search(String word) {
+        TrieNode node = root;
+        for (char ch : word.toCharArray()) {
+            int index = (int) ch - 97;
+            if (node.children[index] == null) {
+                return false;
+            }
+            node = node.children[index];
+        }
+        return node.isEnd;
+    }
+    
+    /** Returns if there is any word in the trie that starts with the given prefix. */
+    public boolean startsWith(String prefix) {
+        TrieNode node = root;
+        for (char ch : prefix.toCharArray()) {
+            int index = (int) ch - 97;
+            if (node.children[index] == null) {
+                return false;
+            }
+            node = node.children[index];
+        }
+        return true;
+    }
+}
+
+/**
+ * Your Trie object will be instantiated and called as such:
+ * Trie obj = new Trie();
+ * obj.insert(word);
+ * boolean param_2 = obj.search(word);
+ * boolean param_3 = obj.startsWith(prefix);
+ */

algorithms/ImplementTriePrefixTree/solution.js

@@ -0,0 +1,78 @@
+/**
+ * Initialize your data structure here.
+ */
+var Trie = function() {
+    this.root = new TrieNode(null)
+};
+
+var TrieNode = function (char) {
+    this.char = char
+    this.children = new Array(26);
+    this.children.fill(null)
+    this.isEnd = false
+}
+
+/**
+ * Inserts a word into the trie. 
+ * @param {string} word
+ * @return {void}
+ */
+Trie.prototype.insert = function(word) {
+    let node = this.root
+    for (let i = 0; i < word.length; i++) {
+        let char = word[i],
+            index = char.charCodeAt(0) - 97
+        
+        if (!node.children[index]) {
+            node.children[index] = new TrieNode(char)
+        }
+        node = node.children[index]
+    }
+    node.isEnd = true
+};
+
+/**
+ * Returns if the word is in the trie. 
+ * @param {string} word
+ * @return {boolean}
+ */
+Trie.prototype.search = function(word) {
+    let node = this.root
+    for (let i = 0; i < word.length; i++) {
+        let char = word[i],
+            index = char.charCodeAt(0) - 97
+        
+        if (!node.children[index]) {
+            return false
+        }
+        node = node.children[index]
+    }
+    return node.isEnd
+};
+
+/**
+ * Returns if there is any word in the trie that starts with the given prefix. 
+ * @param {string} prefix
+ * @return {boolean}
+ */
+Trie.prototype.startsWith = function(prefix) {
+    let node = this.root
+    for (let i = 0; i < prefix.length; i++) {
+        let char = prefix[i],
+            index = char.charCodeAt(0) - 97
+        
+        if (!node.children[index]) {
+            return false
+        }
+        node = node.children[index]
+    }
+    return true
+};
+
+/** 
+ * Your Trie object will be instantiated and called as such:
+ * var obj = Object.create(Trie).createNew()
+ * obj.insert(word)
+ * var param_2 = obj.search(word)
+ * var param_3 = obj.startsWith(prefix)
+ */

algorithms/ImplementTriePrefixTree/solution.py

@@ -0,0 +1,63 @@
+class Trie(object):
+    
+    class TrieNode(object):
+        def __init__(self, char):
+            self.char = char
+            self.children = [None] * 26
+            self.is_end = False
+        
+    
+    def __init__(self):
+        """
+        Initialize your data structure here.
+        """
+        self.root = self.TrieNode(None)
+
+    def insert(self, word):
+        """
+        Inserts a word into the trie.
+        :type word: str
+        :rtype: void
+        """
+        node = self.root
+        for c in word:
+            index = ord(c) - 97
+            if not node.children[index]:
+                node.children[index] = self.TrieNode(c)
+            node = node.children[index]
+        node.is_end = True
+
+    def search(self, word):
+        """
+        Returns if the word is in the trie.
+        :type word: str
+        :rtype: bool
+        """
+        node = self.root
+        for c in word:
+            index = ord(c) - 97
+            if not node.children[index]:
+                return False
+            node = node.children[index]
+        return node.is_end
+
+    def startsWith(self, prefix):
+        """
+        Returns if there is any word in the trie that starts with the given prefix.
+        :type prefix: str
+        :rtype: bool
+        """
+        node = self.root
+        for c in prefix:
+            index = ord(c) - 97
+            if not node.children[index]:
+                return False
+            node = node.children[index]
+        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)