## Facebook Interview Questions

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Answers

- ajay.raj November 09, 2017 in United States`given a binary array, you can flip 0 -> 1 or 1 -> 0 to make all the 1 are in the left part and all the 0 to the right part, return the minimun flip required example 1 1011000 -> 1111000 only need one flip 0 -> 1 example 2 00001 -> 10000 require 2 flips public int findMiniFlip(int[] nums) { } }`

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Facebook SDE1 - 0of 0 votes

AnswersGiven a string s, break s such that every substring of the partition can be found in the dictionary.

- ajay.raj November 05, 2017 in United States

Return the minimum break needed.

Example

Given a String CatMat

Given a dictionary ["Cat", "Mat", "Ca", "tM", "at", "C", "Dog", "og", "Do"]

return 1

we can break the sentences in three ways, as follows:

CatMat = Cat Mat break 1

CatMat = Ca tM at break 2

CatMat = C at Mat break 2

but the first way has the minimum break, thus return 1

public int wordBreak(String s, Set<String> dict) {

// Write your code here

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Facebook SDET - 0of 0 votes

AnswersGiven a 2d grid map of '1's (land) and '0's (water), find the perimeter of each island. 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.

- ajay.raj November 05, 2017 in United States| Report Duplicate | Flag | PURGE

Facebook SDE1 - 0of 0 votes

AnswersTo determine if two graphs have isomorphism or not

- ajay.raj November 05, 2017 in United States| Report Duplicate | Flag | PURGE

Facebook SDE1 - 0of 0 votes

AnswersGive an array A, find the (i, j) pairs that satisfy the condition.

- ajay.raj November 05, 2017 in United States

Condition 1: A [j] = A [i] + 1, Condition 2: j - i is as large as possible

Followup condition 1 is changed to A [j]> A [i]| Report Duplicate | Flag | PURGE

Facebook SDE1 - 0of 0 votes

Answersfind a shortest string to cover all of a list of string,

- ajay.raj November 04, 2017 in United States

For example, [aab, aabb, bc], should return aabbc,

because aab, aabb, bc are all the substring of aabbc| Report Duplicate | Flag | PURGE

Facebook SDE1 - 0of 0 votes

AnswersGiven a linked list with next and random pointer, deepcopy the linked list and return new head.

- me.samyakjain November 03, 2017 in United States

Node {

char val,

Node next,

Node random }

A {

val: ’a’

next: D

random: G}

D {

val: ’d’

next: G

random: A}

G {

val: ’g’

next: null

random: D}

-----------

| |

| V

A -> D -> G -> null

-------------

| |

| V

A' -> D' -> G' -> null| Report Duplicate | Flag | PURGE

Facebook Android Engineer Algorithm - 0of 0 votes

AnswersExplain in detail about your favourite android api.

- me.samyakjain November 03, 2017 in United States| Report Duplicate | Flag | PURGE

Facebook Android Engineer Android - 0of 0 votes

Answersgiven 2 list of interval representing users online offline timestamp e.g (already sorted), find all intervals that both of users are online.

- ajay.raj November 03, 2017 in United States

e.g A= [(3, 5), (7, 11)] B=[(2, 4), (9, 10)] --> [(3, 4), (9, 10)].| Report Duplicate | Flag | PURGE

Facebook SDE1 - 2of 2 votes

AnswerFacebook

- aonecoding November 03, 2017 in United States

-Phone: LC304 & longest arithmetic sequence. Return the sequence.| Report Duplicate | Flag | PURGE

Facebook Software Engineer Algorithm - 0of 0 votes

AnswersGiven an array of integers and k, find the difference between the number of the strictly increasing number of subarrays (of size more than one) and the number of the strictly decreasing subarray in the window of size k. your method should be time and space efficent

- ajay.raj November 03, 2017 in United States

example

int[] nums = {188930, 194123, 201345, 154243, 154243};

int k = 3;

Output

3, 0, -1

Explanation

For the first window of [188930, 194123, 201345], there are 3 increasing subranges ([188930, 194123, 201345], [188930, 194123], and [194123, 201345]) and 0 decreasing, so the answer is 3. For the second window of [194123, 201345, 154243], there is 1 increasing subrange and 1 decreasing, so the answer is 0. For the third window of [201345, 154243, 154243], there is 1 decreasing subrange and 0 increasing, so the answer is -1.

public int[] getdiff(int[] nums, int l){

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Facebook SDE1 - 0of 0 votes

Answers

- ajay.raj October 31, 2017 in United States`There is an unordered interval stream, write a method, returns the total length that all intervals cover by now class Interval{ int start; int end; } public List<Integer> countCoverLength(Iterator<Interval> stream){ }`

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Facebook SDE1 - 0of 0 votes

Answers‘.’Matches any single character,' * 'Matches any sequence of characters (including the empty sequence).

- ajay.raj October 28, 2017 in United States

There are two input, one is string pattern, and the other is dictionary like dict = ["cat", "cats", "and", "sand", "dog"].

return a boolean: whether to find a dictionary in the pattern match the word

eg: dict = ["cat", "cats", "and", "sand", "dog"].

pattern = "* t", -> true (can match cat)

pattern = ".a *" -> true (can match cat, cats, can also match sand, because * can also express empty sequence)| Report Duplicate | Flag | PURGE

Facebook SDE1 - 0of 0 votes

AnswersHow would you store and retrieve values in Memcache if the values are larger than the individual value size allowed by Memcache?

- ajay.raj October 25, 2017 in United States| Report Duplicate | Flag | PURGE

Facebook SDE1 - 2of 2 votes

Answersnode {

- ajay.raj October 23, 2017 in United States

node * left, * right;

}

Given a list of node to determine whether the node in the list can form a valid binary tree. several points of judgment

1. need to ensure that all left, right pointer point to the node inside list

2. no cycle

3. All node must be connected

Boolean isValidTree(List<Node> list){}| Report Duplicate | Flag | PURGE

Facebook Software Developer - 1of 1 vote

AnswersGiven a matrix of N * M, given the coordinates (x, y) present in a matrix,

- ajay.raj October 23, 2017 in United States

Find the number of paths that can reach (0, 0) from the (x, y) points with k steps (requires exactly k, k> = 0)

From each point you can go up, down, left and right in four directions.

For example, the following matrix:

----------

0 0 0 0 0

0 0 0 0 0

0 0 0 0 0

0 0 0 0 0

(x, y) = (1, 1), k = 2, the output is 2| Report Duplicate | Flag | PURGE

Facebook Software Developer - 0of 0 votes

AnswersFind all words [A-Z] in a dictionary (about 1M words) that are made of a subset (in any order) of the chars in the input parameter [A-Z].

- ajay.raj October 19, 2017 in United States

ex: input "ACRAT" (10 to 20 chars, up to 30 worst case)

matching words: "A", "CAR", "ACA", "ART", "RAC".

non-matching words: "BAR", "AAA"

follow up : the input is a list of words. Return a list of words that each

list is formed by exactly the characters in the input list.

For example: two lists {“DEBIT”, “CARD”} and{“BAD”, “CREDIT”}

are formed by the same exact group of characters.| Report Duplicate | Flag | PURGE

Facebook SDE1 - 0of 0 votes

AnswersGiven a sorted list of integers, square the elements and give the output in sorted order.

- nra October 19, 2017 in United States| Report Duplicate | Flag | PURGE

Facebook Software Engineer - 0of 0 votes

AnswersFind the distance between the farthest two elements in a binary tree.

- nra October 19, 2017 in United States| Report Duplicate | Flag | PURGE

Facebook Software Engineer Algorithm - 0of 0 votes

AnswersGiven a string separated by a space like "123456 abc+efg" determine

- ajay.raj October 18, 2017 in United States

the solution by mapping integers to letters like a:1, b:2, c:3, d:4, e:5, f:6.

The only operations allowed were + or -. So the calculated solution

that made the tests pass was 123+456 = 579.| Report Duplicate | Flag | PURGE

Facebook SDE1 - 0of 0 votes

AnswersHow many subsets of a given array sum to zero?

- ajay.raj October 18, 2017 in United States| Report Duplicate | Flag | PURGE

Facebook SDE1 - 0of 0 votes

AnswersGiven numbers 1 through 52, take 5 unique numbers and determine

- ajay.raj October 18, 2017 in United States

if the number 42 can be made using any combination of addition (+),

subtraction (-), multiplication (*), and division (/) on those 5 numbers| Report Duplicate | Flag | PURGE

Facebook SDE1 - 1of 1 vote

Answers/* Intersection of two sorted interval lists, A=[(1,2), (5,7)..]

B=[(2,6)...] return [(5,6)..] */

- ajay.raj October 09, 2017 in United States`import java.util.*; class Interval{ int start; int end; public Interval(int start, int end){ this.start = start; this.end = end; } } class Solution { public List<Interval> Intersection(Interval[] i1, Interval[] i2) {}`

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Facebook SDE1 - 0of 0 votes

Answers* Given a string on length N. You can swap only the adjacent elements

- ajay.raj October 02, 2017 in United States

and each element can be swapped atmost once.

Find the no of permutations of the string that can be generated after

performing the swaps as mentioned.

Ex –

string – “12345”

Ans = 8

Explanations- (All the permutations)

12345

21345

13245

12435

12354

21435

13254

21354| Report Duplicate | Flag | PURGE

Facebook SDE1 - 0of 0 votes

AnswersGiven an array of n positive integers, find the number of subarrays

- ajay.raj October 02, 2017 in United States

such that product of the elements of those subarrays are less than k.

For eg. Arr= {2, 3, 6} k=10

No of such subarrays= 4| Report Duplicate | Flag | PURGE

Facebook SDE1 - 1of 1 vote

AnswersPrint the levels of a binary tree in reverse order using stack and recursion

`Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root). For example: Given binary tree 3 / \ 9 20 / \ 15 7 return its bottom-up level order traversal as: [ [15,7], [9,20], [3] ]`

public List<List<Integer>> levelOrderBottom(TreeNode root) {

- ajay.raj October 02, 2017 in United States

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Facebook SDE1 - 0of 0 votes

Answersgiven an array, find whether there exists 3 elements a,b,c in it such that a+b=c using efficient method.

- ajay.raj October 02, 2017 in United States| Report Duplicate | Flag | PURGE

Facebook SDE1 - 0of 0 votes

AnswersYou are provided a BST, which is corrupted. One of the nodes in it has 2 parents.

- ajay.raj October 02, 2017 in United States

Let’s say those are parent 1 and parent 2. It is ensured that none

of these parents will be the ancestor of the other. Identify the node,

and remove the link of the wrong parent.| Report Duplicate | Flag | PURGE

Facebook SDE1 - 1of 1 vote

Answersgiven an array of strings and characters, make the largest string possible.

- ajay.raj October 02, 2017 in United States

The resultant string should be a combination of the strings given in the array.

The given array

of characters may contain repeated elements.

Example – Given char array – {a,a,b,c,d,d,e,c} and given strings

– {abba, aabc, de, cde} the

ans is aabccde| Report Duplicate | Flag | PURGE

Facebook SDET - 1of 1 vote

AnswersGiven an adjacency matrix of a directed graph, find the number of cycles in the graph

- ajay.raj October 02, 2017 in United States| Report Duplicate | Flag | PURGE

Facebook SDE1

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