Facebook FEE Intern

• Given 2 identical DOM trees (but not equal) and one element of the first DOM tree, how would you find this element in the second DOM tree?

• Write an array flatten function.

• Write an emitter class:

• Can you write a function that deeply flattens an array?

• Given two identical DOM tree structures, A and B, and a node from A, find the corresponding node in B.

• Explain the concept of ES6 Promises to a 5-year-old.

• What are the advantages of using ES6 maps over objects? What about using ES6 sets over arrays?

• design/code a poll widget

• Given a grid of characters output a decoded message. The message for the following would be IROCKA. (diagonally down right and diagonally up right if you can't go further .. you continue doing this)

Encoded message:
I B C A L K A
D R F C A E A
G H O E L A D

Decoded message:
I R O C L E D

• you should know event bubbling, debounce (its variant)... know how to code it
• Poll Widget question (just know your positioning, relative, static etc know the differences inside out).
• If you have 500 revisions of a program, write a program that will find and return the FIRST bad revision given a isBad(revision i) function.
• Given an input array and another array that describes a new index for each element, mutate the input array so that each element ends up in their new index. Discuss the runtime of the algorithm and how you can be sure there won't be any infinite loops.
• Given a picture, how would you hide/show a child picture on hovering on this parent?
• How would you ensure clicking on this picture would go to a specific link?
• How would you ensure the child is positioned in the top right of the parent picture?
• Given an array, return it's flattened structure(skip objects)
• what is 'this', what is closure, var vs const vs let, DOM tree
• Basic graph algo & DS style whiteboarding question
• Front-end related algorithms and DS questions
• Implement a simple store class with set(Node, value), get(Node) and has(Node) methods, which store a given Nodes with corresponding values.
• Implement a square root function.
• how could you implement debouncing?
• how could you implement throttling?
• Say you wanted the handleScroll function to be called only after 200ms has passed between scroll events
• Build a puzzle game with Javascript
• function currying
• polyfill for bind
• hoisting

• 10 Regular Expression Matching 22.0% Hard
• 13 Roman to Integer 39.2% Easy
• 15 3Sum 18.8% Medium
• 17 Letter Combinations of a Phone Number 28.6% Medium
• 20 Valid Parentheses 29.3% Easy
• 23 Merge k Sorted Lists 23.3% Hard
• 25 Reverse Nodes in k-Group 27.5% Hard
• 26 Remove Duplicates from Sorted Array 33.4% Easy
• 28 Implement strStr() 24.8% Easy
• 33 Search in Rotated Sorted Array 30.2% Hard
• 38 Count and Say 28.9% Easy
• 43 Multiply Strings 23.4% Medium
• 44 Wildcard Matching 17.4% Hard
• 49 Group Anagrams 27.4% Medium
• 50 Pow(x, n) 27.9% Medium
• 56 Merge Intervals 25.3% Hard
• 57 Insert Interval 23.8% Hard
• 67 Add Binary 27.4% Easy
• 69 Sqrt(x) 25.2% Medium
• 71 Simplify Path 21.9% Medium
• 75 Sort Colors 34.7% Medium
• 76 Minimum Window Substring 21.2% Hard
• 78 Subsets 31.3% Medium
• 79 Word Search 22.9% Medium
• 80 Remove Duplicates from Sorted Array II 32.7% Medium
• 85 Maximal Rectangle 23.4% Hard
• 88 Merge Sorted Array 30.0% Easy
• 90 Subsets II 30.5% Medium
• 91 Decode Ways 17.5% Medium
• 98 Validate Binary Search Tree 20.9% Medium
• 102 Binary Tree Level Order Traversal 32.7% Easy
• 117 Populating Next Right Pointers in Each Node II 32.8% Hard
• 121 Best Time to Buy and Sell Stock 36.0% Easy
• 125 Valid Palindrome 23.8% Easy
• 127 Word Ladder 19.6% Medium
• 128 Longest Consecutive Sequence 32.1% Hard
• 133 Clone Graph 24.9% Medium
• 139 Word Break 25.2% Medium
• 146 LRU Cache 15.8% Hard
• 157 Read N Characters Given Read4 29.5% Easy
• 158 Read N Characters Given Read4 II – Call multiple times 23.4% Hard
• 161 One Edit Distance 28.4% Medium
• 168 Excel Sheet Column Title 21.6% Easy
• 173 Binary Search Tree Iterator 34.5% Medium
• 200 Number of Islands 27.6% Medium
• 206 Reverse Linked List 39.4% Easy
• 208 Implement Trie (Prefix Tree) 25.3% Medium
• 209 Minimum Size Subarray Sum 26.8% Medium
• 210 Course Schedule II 21.0% Medium
• 211 Add and Search Word – Data structure design 20.2% Medium
• 215 Kth Largest Element in an Array 33.1% Medium
• 218 The Skyline Problem 22.0% Hard
• 221 Maximal Square 23.5% Medium
• 234 Palindrome Linked List 28.0% Easy
• 235 Lowest Common Ancestor of a Binary Search Tree 37.7% Easy
• 236 Lowest Common Ancestor of a Binary Tree 28.8% Medium
• 238 Product of Array Except Self 42.6% Medium
• 252 Meeting Rooms 41.6% Easy
• 253 Meeting Rooms II 34.6% Medium
• 257 Binary Tree Paths 28.4% Easy
• 261 Graph Valid Tree 32.5% Medium
• 265 Paint House II 35.6% Hard
• 269 Alien Dictionary 22.9% Hard
• 273 Integer to English Words 18.7% Hard
• 274 H-Index 29.3% Medium
• 275 H-Index II 32.5% Medium
• 277 Find the Celebrity 35.1% Medium
• 278 First Bad Version 22.4% Easy
• 282 Expression Add Operators 24.8% Hard
• 283 Move Zeroes 44.0% Easy
• 285 Inorder Successor in BST 35.6% Medium
• 286 Walls and Gates 37.2% Medium
• 297 Serialize and Deserialize Binary Tree 27.8% Hard
• 301 Remove Invalid Parentheses 31.9% Hard
• 311 Sparse Matrix Multiplication 47.2% Medium
• 314 Binary Tree Vertical Order Traversal 30.3% Medium
• 325 Maximum Size Subarray Sum Equals k 39.9% Easy
• 334 Increasing Triplet Subsequence 33.2% Medium

• Two Sum 23.0% Easy
• Add Two Numbers 23.0% Medium
• Longest Substring Without Repeating Characters 21.9% Medium
• Longest Palindromic Substring 23.0% Medium
• String to Integer (atoi) 13.5% Easy
• 3Sum 18.8% Medium
• Letter Combinations of a Phone Number 28.6% Medium
• Valid Parentheses 29.3% Easy
• Merge Two Sorted Lists 35.4% Easy
• Merge k Sorted Lists 23.3% Hard
• Trapping Rain Water 32.2% Hard
• Rotate Image 34.6% Medium
• Group Anagrams 27.4% Medium
• Subsets 31.3% Medium
• Gray Code 36.3% Medium
• Validate Binary Search Tree 20.9% Medium
• Binary Tree Level Order Traversal 32.7% Easy
• Best Time to Buy and Sell Stock 36.0% Easy
• Word Ladder II 13.6% Hard
• Word Ladder 19.6% Medium
• Copy List with Random Pointer 26.1% Hard
• Word Break 25.2% Medium
• Linked List Cycle 37.0% Medium
• LRU Cache 15.8% Hard
• Min Stack 22.0% Easy
• Intersection of Two Linked Lists 30.2% Easy
• Two Sum II – Input array is sorted 47.8% Medium
• Reverse Words in a String II 29.1% Medium
• Binary Tree Right Side View 34.3% Medium
• Number of Islands 27.6% Medium
• Count Primes 24.2% Easy
• Reverse Linked List 39.4% Easy
• Kth Largest Element in an Array 33.1% Medium
• Palindrome Linked List 28.0% Easy
• Lowest Common Ancestor of a Binary Search Tree 37.7% Easy
• Lowest Common Ancestor of a Binary Tree 28.8% Medium
• Product of Array Except Self 42.6% Medium
• Sliding Window Maximum 27.3% Hard
• Search a 2D Matrix II 34.4% Medium
• Valid Anagram 41.7% Easy
• Serialize and Deserialize Binary Tree 27.8% Hard