solve: implement trie prefix tree

Author: wogha95

implement-trie-prefix-tree/wogha95.js

@@ -0,0 +1,81 @@
+function Node() {
+  this.value = null;
+  this.wordGraph = new Map();
+}
+
+var Trie = function () {
+  this.wordGraph = new Map();
+};
+
+/**
+ * TC: O(W)
+ * SC: O(W)
+ * W: word.length
+ */
+
+/**
+ * @param {string} word
+ * @return {void}
+ */
+Trie.prototype.insert = function (word) {
+  let pointer = this;
+  for (const w of word) {
+    if (!pointer.wordGraph.has(w)) {
+      pointer.wordGraph.set(w, new Node());
+    }
+    pointer = pointer.wordGraph.get(w);
+  }
+  pointer.value = word;
+};
+
+/**
+ * TC: O(W)
+ * SC: O(1)
+ * W: word.length
+ */
+
+/**
+ * @param {string} word
+ * @return {boolean}
+ */
+Trie.prototype.search = function (word) {
+  let pointer = this;
+  for (const w of word) {
+    if (!pointer.wordGraph.has(w)) {
+      return false;
+    } else {
+      pointer = pointer.wordGraph.get(w);
+    }
+  }
+  return pointer.value === word;
+};
+
+/**
+ * TC: O(P)
+ * SC: O(1)
+ * P:prefix.length
+ */
+
+/**
+ * @param {string} prefix
+ * @return {boolean}
+ */
+Trie.prototype.startsWith = function (prefix) {
+  let pointer = this;
+  for (const p of prefix) {
+    if (!pointer.wordGraph.has(p)) {
+      return false;
+    } else {
+      pointer = pointer.wordGraph.get(p);
+    }
+  }
+  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)
+ */