Merge pull request knaxus#117 from knaxus/trie

Trie problems

Author: TheSTL

README.md

@@ -31,16 +31,16 @@ Collection of interview questions with Unit Tests. Problems includes Data Struct
   - [Implement 2 Stacks using Single Array](src/_DataStructures_/Stack/2-stacks-using1-array)
   - [Sort a Stack](src/_DataStructures_/Stack/sort-a-stack)
 
-* [Queue](src/_DataStructures_/Queue)
+- [Queue](src/_DataStructures_/Queue)
 
   - [Weave](src/_DataStructures_/Queue/weave)
   - [Reverse First K Elements of a Queue](src/_DataStructures_/Queue/reverse-first-k)
   - [Generate all Binary Numbers from 1 to N](src/_DataStructures_/Queue/generate-binary-number)
   - [Queue using Stack](src/_DataStructures_/Queue/queue-using-stack)
 
-* [Doubly Linked List](src/_DataStructures_/DoublyLinkedList)
+- [Doubly Linked List](src/_DataStructures_/DoublyLinkedList)
 
-* [Trees](src/_DataStructures_/Trees)
+- [Trees](src/_DataStructures_/Trees)
   - [Binary Tree (creation using level order)](src/_DataStructures_/Trees/BinaryTree)
   - [Binary Search Tree](src/_DataStructures_/Trees/BinarySearchTree)
     - [Find k<sup>th</sup> maximum in a BinarySearchTree](src/_DataStructures_/Trees/BinarySearchTree/find-kth-max)
@@ -50,6 +50,10 @@ Collection of interview questions with Unit Tests. Problems includes Data Struct
     - [Find k Nodes from Root of BST](src/_DataStructures_/Trees/BinarySearchTree/find-k-nodes-from-root)
   - [Suffix Tree](src/_DataStructures_/SuffixTree)
   - [Trie](src/_DataStructures_/Trees/Trie)
+    - [Total words count count in a Trie](src/_DataStructures_/Trees/Trie/total-words-in-trie)
+    - [Unique words count in a Trie](src/_DataStructures_/Trees/Trie/unique-word-count)
+    - [All the words from a Trie](src/_DataStructures_/Trees/Trie/all-words-in-trie)
+    - [Unique words in a Trie](src/_DataStructures_/Trees/Trie/get-unique-words)
 
 ### Logical Problems
 

src/_DataStructures_/Trees/Trie/Node.js

@@ -3,6 +3,7 @@ class TrieNode {
     this.char = char;
     this.children = [];
     this.isEndOfWord = false;
+    this.wordCount = 0;
 
     // mark all the alphabets as null
     for (let i = 0; i < 26; i += 1) this.children[i] = null;
@@ -15,6 +16,10 @@ class TrieNode {
   unmarkAsLeaf() {
     this.isEndOfWord = false;
   }
+
+  increaseCount() {
+    this.wordCount += 1;
+  }
 }
 
 module.exports = TrieNode;

src/_DataStructures_/Trees/Trie/all-words-in-trie/index.js

@@ -0,0 +1,46 @@
+// eslint-disable-next-line no-unused-vars
+const Trie = require('../index');
+
+function getAllWords(root, level, word) {
+  let result = [];
+
+  if (!root) return result;
+
+  if (root.isEndOfWord) {
+    let temp = '';
+    for (let i = 0; i < level; i += 1) {
+      temp += String(word[i]);
+    }
+    // get the count and push all the occurences
+    const res = [];
+    for (let i = 0; i < root.wordCount; i += 1) {
+      res.push(temp);
+    }
+    result = [...result, ...res];
+  }
+
+  for (let i = 0; i < 26; i += 1) {
+    if (root.children[i] !== null) {
+      // eslint-disable-next-line no-param-reassign
+      word[level] = String.fromCharCode(i + 'a'.charCodeAt(0));
+      result = [...result, ...getAllWords(root.children[i], level + 1, word)];
+    }
+  }
+  return result;
+}
+
+function allWordsFromTrie(root) {
+  const word = []; // char arr to store a word
+  for (let i = 0; i < 26; i += 1) {
+    word[i] = null;
+  }
+  return getAllWords(root, 0, word);
+}
+
+// const words = ['bed', 'ball', 'apple', 'java', 'javascript', 'bed'];
+// const trie = new Trie();
+
+// words.forEach(word => trie.insert(word));
+// console.log(allWordsFromTrie(trie.root));
+
+module.exports = allWordsFromTrie;

src/_DataStructures_/Trees/Trie/get-unique-words/index.js

@@ -0,0 +1,40 @@
+const Trie = require('../index');
+
+function getAllUniqueWords(root, level, word) {
+  let result = [];
+
+  if (!root) return result;
+
+  if (root.isEndOfWord) {
+    let temp = '';
+    for (let i = 0; i < level; i += 1) {
+      temp += String(word[i]);
+    }
+    result = [...result, temp];
+  }
+
+  for (let i = 0; i < 26; i += 1) {
+    if (root.children[i]) {
+      // eslint-disable-next-line no-param-reassign
+      word[level] = String.fromCharCode(i + 'a'.charCodeAt(0));
+      result = [...result, ...getAllUniqueWords(root.children[i], level + 1, word)];
+    }
+  }
+  return result;
+}
+
+function allUniqueWordsFromTrie(root) {
+  const word = []; // char arr to store a word
+  for (let i = 0; i < 26; i += 1) {
+    word[i] = null;
+  }
+  return getAllUniqueWords(root, 0, word);
+}
+
+// const words = ['bed', 'ball', 'apple', 'java', 'javascript', 'bed'];
+// const trie = new Trie();
+
+// words.forEach(word => trie.insert(word));
+// console.log(allUniqueWordsFromTrie(trie.root));
+
+module.exports = allUniqueWordsFromTrie;

src/_DataStructures_/Trees/Trie/index.js

@@ -32,6 +32,7 @@ class Trie {
     // when we are done with inserting all the character of the word,
     // mark the node as end leaf
     currentNode.markAsLeaf();
+    currentNode.increaseCount();
     return true;
   }
 

src/_DataStructures_/Trees/Trie/total-words-in-trie/index.js

@@ -0,0 +1,23 @@
+// eslint-disable-next-line no-unused-vars
+const Trie = require('../index');
+
+function totalWords(root) {
+  let result = 0;
+  if (root.isEndOfWord) {
+    result += root.wordCount;
+  }
+  for (let i = 0; i < 26; i += 1) {
+    if (root.children[i] !== null) {
+      result += totalWords(root.children[i]);
+    }
+  }
+  return result;
+}
+
+// const words = ['bed', 'ball', 'apple', 'java', 'javascript', 'bed'];
+// const trie = new Trie();
+
+// words.forEach(word => trie.insert(word));
+// console.log(totalWords(trie.root));
+
+module.exports = totalWords;

src/_DataStructures_/Trees/Trie/unique-word-count/index.js

@@ -0,0 +1,23 @@
+/* eslint-disable no-unused-vars */
+const Trie = require('../index');
+
+function uniqueWordCount(root) {
+  let result = 0;
+  if (root.isEndOfWord) {
+    result += 1;
+  }
+  for (let i = 0; i < 26; i += 1) {
+    if (root.children[i]) {
+      result += uniqueWordCount(root.children[i]);
+    }
+  }
+  return result;
+}
+
+// const words = ['bed', 'ball', 'apple', 'java', 'javascript', 'bed'];
+// const trie = new Trie();
+
+// words.forEach(word => trie.insert(word));
+// console.log(uniqueWordCount(trie.root));
+
+module.exports = uniqueWordCount;