implement trie (prefix tree) solution

Author: hyer0705

implement-trie-prefix-tree/hyer0705.ts

@@ -0,0 +1,69 @@
+class TNode {
+  isEndOf: boolean;
+  children: Map<string, TNode>;
+
+  constructor() {
+    this.isEndOf = false;
+    this.children = new Map<string, TNode>();
+  }
+}
+
+class Trie {
+  private root: TNode;
+
+  constructor() {
+    this.root = new TNode();
+  }
+
+  insert(word: string): void {
+    let currentNode: TNode = this.root;
+
+    for (const ch of word) {
+      if (currentNode.children.has(ch)) {
+        currentNode = currentNode.children.get(ch)!;
+      } else {
+        const newNode = new TNode();
+
+        currentNode.children.set(ch, newNode);
+        currentNode = currentNode.children.get(ch)!;
+      }
+    }
+    currentNode.isEndOf = true;
+  }
+
+  search(word: string): boolean {
+    let currentNode = this.root;
+
+    for (const ch of word) {
+      if (!currentNode.children.has(ch)) {
+        return false;
+      }
+
+      currentNode = currentNode.children.get(ch)!;
+    }
+
+    return currentNode.isEndOf;
+  }
+
+  startsWith(prefix: string): boolean {
+    let currentNode = this.root;
+
+    for (const ch of prefix) {
+      if (!currentNode.children.has(ch)) {
+        return false;
+      }
+
+      currentNode = currentNode.children.get(ch)!;
+    }
+
+    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)
+ */