trie ds added

Author: surajmaity1

Trie/trie.js

@@ -0,0 +1,103 @@
+class Node {
+  constructor() {
+    this.links = new Array(26);
+    this.flag = false;
+  }
+
+  // Check whether the node contains the specific key (character)
+  containsKey(character) {
+    return (
+      this.links[character.charCodeAt(0) - "a".charCodeAt(0)] !== undefined
+    );
+  }
+
+  // Insert a new node with the specific key (character)
+  insert(character, node) {
+    return (this.links[character.charCodeAt(0) - "a".charCodeAt(0)] = node);
+  }
+
+  // Fetch the node with the specific key (character)
+  get(character) {
+    return this.links[character.charCodeAt(0) - "a".charCodeAt(0)];
+  }
+
+  // Set the node as end of the word
+  setEnd() {
+    this.flag = true;
+  }
+
+  // Get the flag of the node that helps to identify it's end of word or not
+  getEnd() {
+    return this.flag;
+  }
+}
+
+export class Trie {
+  constructor() {
+    this.root = new Node();
+  }
+
+  // O(k) where k is length of string
+  insert(word) {
+    let node = this.root;
+
+    for (let index = 0; index < word.length; index++) {
+      const character = word[index];
+
+      // character is not present in the trie
+      if (!node.containsKey(character)) {
+        node.insert(character, new Node());
+      }
+
+      // As character is present, move to next node
+      node = node.get(character);
+    }
+
+    // Mark the end of the word
+    node.setEnd();
+  }
+
+  // O(k) where k is length of string
+  startsWith(word) {
+    let traverse = this.root;
+
+    for (let index = 0; index < word.length; index++) {
+      const element = word[index];
+
+      if (!traverse.containsKey(element)) {
+        return false;
+      }
+
+      traverse = traverse.get(element);
+    }
+
+    return true;
+  }
+
+  // O(k) where k is length of string
+  search(word) {
+    let traverse = this.root;
+
+    for (let index = 0; index < word.length; index++) {
+      const element = word[index];
+
+      if (!traverse.containsKey(element)) {
+        return false;
+      }
+
+      traverse = traverse.get(element);
+    }
+
+    return traverse.getEnd();
+  }
+}
+
+function main() {
+  const trie = new Trie();
+  trie.insert("apple");
+  trie.insert("boy");
+  trie.insert("apply");
+
+}
+
+main();