Add implement-trie-prefix-tree solution in TypeScript

Author: Jeehay28

implement-trie-prefix-tree/Jeehay28.ts

@@ -0,0 +1,64 @@
+// Time Complexity: O(n)
+
+class TrieNode {
+  children: { [key: string]: TrieNode };
+  ending: boolean;
+
+  constructor(ending = false) {
+    this.children = {};
+    this.ending = ending;
+  }
+}
+
+class Trie {
+  root: TrieNode;
+
+  constructor() {
+    this.root = new TrieNode();
+  }
+
+  insert(word: string): void {
+    let node = this.root;
+
+    for (const ch of word) {
+      if (!(ch in node.children)) {
+        node.children[ch] = new TrieNode();
+      }
+      node = node.children[ch];
+    }
+    node.ending = true;
+  }
+
+  search(word: string): boolean {
+    let node = this.root;
+
+    for (const ch of word) {
+      if (!(ch in node.children)) {
+        return false;
+      }
+      node = node.children[ch];
+    }
+    return node.ending;
+  }
+
+  startsWith(prefix: string): boolean {
+    let node = this.root;
+
+    for (const ch of prefix) {
+      if (!(ch in node.children)) {
+        return false;
+      }
+
+      node = node.children[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)
+ */