update: TrieNode, insert() in Trie

Author: ashokdey

src/_DataStructures_/Trees/Trie/Node.js

@@ -0,0 +1,20 @@
+class TrieNode {
+  constructor(char) {
+    this.char = char;
+    this.children = [];
+    this.isEndOfWord = false;
+
+    // mark all the alphabets as null
+    for (let i = 0; i < 26; i += 1) this.children[i] = null;
+  }
+
+  markAsLeaf() {
+    this.isEndOfWord = true;
+  }
+
+  unmarkAsLeaf() {
+    this.isEndOfWord = false;
+  }
+}
+
+module.exports = TrieNode;

src/_DataStructures_/Trees/Trie/index.js

@@ -0,0 +1,39 @@
+const Node = require('./Node');
+
+class Trie {
+  constructor() {
+    this.root = new Node('');
+  }
+
+  insert(key) {
+    if (!key) {
+      return false;
+    }
+
+    // convert to lower case
+    // keys are basically words
+    const word = key.toLowerCase();
+    let currentNode = this.root;
+
+    for (let level = 0; level < word.length; level += 1) {
+      const index = this.getIndexOfChar(word[level]);
+      if (!currentNode.children[index]) {
+        currentNode.children[index] = new Node(word[level]);
+      }
+      currentNode = currentNode.children[index];
+    }
+
+    // when we are done with inserting all the character of the word,
+    // mark the node as end leaf
+    currentNode.markAsLeaf();
+    return true;
+  }
+
+  // helper to get the index of a character
+  // eslint-disable-next-line class-methods-use-this
+  getIndexOfChar(char) {
+    return char.charCodeAt(0) - 'a'.charCodeAt(0);
+  }
+}
+
+module.exports = Trie;