Merge remote-tracking branch 'up/master'

Author: niyonx

.gitignore

@@ -1,2 +1,3 @@
 node_modules/
-coverage/
+coverage/
+.vs/

src/_DataStructures_/Trees/BinaryTree/bottom-view-binary-tree/index.js

@@ -0,0 +1,39 @@
+const Queue = require('../../../Queue');
+
+// Determines the bottom view of a binary tree
+// Takes a BinaryTree as a parameter
+// Returns an integer array
+// Time complexity: O(n) where n is the number of nodes in the tree
+
+module.exports = function bottomView(binaryTree) {
+  if (binaryTree == null || binaryTree.root == null) {
+    return [];
+  }
+
+  // root's horizontal distance = 0
+  const horizontalDistance = 0;
+
+  // create a map to track most recent visited nodes per hd
+  const hdToNodeValue = new Map();
+
+  // perform bfs
+  const q = new Queue();
+  q.enqueue([binaryTree.root, horizontalDistance]);
+
+  while (q.length() > 0) {
+    const currentNodeTuple = q.dequeue();
+    const currentNode = currentNodeTuple[0];
+    const currentHd = currentNodeTuple[1];
+    hdToNodeValue.set(currentHd, currentNode.value);
+
+    if (currentNode.leftChild != null && currentNode.leftChild.value != null) {
+      q.enqueue([currentNode.leftChild, currentHd - 1]);
+    }
+
+    if (currentNode.rightChild != null && currentNode.rightChild.value != null) {
+      q.enqueue([currentNode.rightChild, currentHd + 1]);
+    }
+  }
+
+  return Array.from(hdToNodeValue.values());
+};

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

@@ -1,6 +1,3 @@
-/* eslint-disable no-unused-vars */
-const Trie = require('../index');
-
 function uniqueWordCount(root) {
   let result = 0;
   if (root.isEndOfWord) {
@@ -14,10 +11,4 @@ function uniqueWordCount(root) {
   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;

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

@@ -0,0 +1,26 @@
+const Trie = require('../index');
+const uniqueWordCount = require('.');
+
+describe('Trie Unique Word Count', () => {
+  it('counts an empty trie', () => {
+    const trie = new Trie();
+    const wordCount = uniqueWordCount(trie.root);
+    expect(wordCount).toEqual(0);
+  });
+
+  it('counts unique words', () => {
+    const trie = new Trie();
+    const words = ['one', 'two', 'three', 'four'];
+    words.forEach(word => trie.insert(word));
+    const wordCount = uniqueWordCount(trie.root);
+    expect(wordCount).toEqual(4);
+  });
+
+  it('does not count duplicate words', () => {
+    const trie = new Trie();
+    const words = ['one', 'one', 'two', 'three'];
+    words.forEach(word => trie.insert(word));
+    const wordCount = uniqueWordCount(trie.root);
+    expect(wordCount).toEqual(3);
+  });
+});