Interviewing at Facebook — On-Site JavaScript Technical Interview Questions

Jan 29 · 2 min read

Here are some questions from an on-site technical interview at Facebook in 2019.

Easy

You are a product manager and currently leading a team to develop a new product. Unfortunately, the latest version of your product fails the quality check. Since each version is developed based on the previous version, all the versions after a bad version are also bad.

Suppose you have `n` versions `[1, 2, ..., n]` and you want to find out the first bad one, which causes all the following ones to be bad.

You are given an API `bool isBadVersion(version)` which will return whether `version` is bad. Implement a function to find the first bad version. You should minimize the number of calls to the API.

Example:

`Given n = 5, and version = 4 is the first bad version.call isBadVersion(3) -> falsecall isBadVersion(5) -> truecall isBadVersion(4) -> trueThen 4 is the first bad version.`

Medium

Design a data structure that supports the following two operations:

`void addWord(word)bool search(word)`

search(word) can search a literal word or a regular expression string containing only letters `a-z` or `.`. A `.` means it can represent any one letter.

Example:

`addWord("bad")addWord("dad")addWord("mad")search("pad") -> falsesearch("bad") -> truesearch(".ad") -> truesearch("b..") -> true`

Note:
You may assume that all words are consist of lowercase letters `a-z`.

Given a 2d grid map of `'1'`s (land) and `'0'`s (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water.

Example 1:

`Input:11110110101100000000Output: 1`

Example 2:

`Input:11000110000010000011Output: 3`

Hard

Remove the minimum number of invalid parentheses in order to make the input string valid. Return all possible results.

Note: The input string may contain letters other than the parentheses `(` and `)`.

Example 1:

`Input: "()())()"Output: ["()()()", "(())()"]`

Example 2:

`Input: "(a)())()"Output: ["(a)()()", "(a())()"]`

Example 3:

`Input: ")("Output: [""]`

Good luck!

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