trie

Author: dingjy94

dataStructure/trie/trie.js

@@ -0,0 +1,76 @@
+/**
+ * Initialize your data structure here.
+ */
+const TrieNode = function (char) {
+  this.val = char;
+  this.map = new Map();
+  this.isEnd = false;
+};
+
+var Trie = function () {
+  this.root = new TrieNode(null);
+};
+
+/**
+ * Inserts a word into the trie.
+ * @param {string} word
+ * @return {void}
+ */
+Trie.prototype.insert = function (word) {
+  const charArr = word.split('');
+  let pointer = this.root;
+  for (let char of charArr) {
+    if (!pointer.map.has(char)) {
+      pointer.map.set(char, new TrieNode(char));
+    }
+
+    pointer = pointer.map.get(char);
+  }
+  pointer.isEnd = true;
+};
+
+/**
+ * Returns if the word is in the trie.
+ * @param {string} word
+ * @return {boolean}
+ */
+Trie.prototype.search = function (word) {
+  const charArr = word.split('');
+  let pointer = this.root;
+  for (let char of charArr) {
+    if (!pointer.map.has(char)) {
+      return false;
+    }
+
+    pointer = pointer.map.get(char);
+  }
+
+  return pointer.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) {
+  const charArr = prefix.split('');
+  let pointer = this.root;
+  for (let char of charArr) {
+    if (!pointer.map.has(char)) {
+      return false;
+    }
+
+    pointer = pointer.map.get(char);
+  }
+
+  return true;
+};
+
+/**
+ * Your Trie object will be instantiated and called as such:
+ * var obj = new Trie()
+ * obj.insert(word)
+ * var param_2 = obj.search(word)
+ * var param_3 = obj.startsWith(prefix)
+ */