Facebook Interview Questions
- 2of 2 votes
AnswersGIven a string "str" and pair of "N" swapping indices, generate a lexicographically largest string. Swapping indices can be reused any number times.
- uvm March 15, 2016 in United States
Eg 1)
String = "abdc"
Indices:
(1,4)
(3,4)
Answer:
cdba, cbad, dbac,dbca
you should print only "dbca" which is lexicographically largest.| Report Duplicate | Flag | PURGE
Facebook SDE-2 Algorithm - 4of 4 votes
AnswersGiven the root of a binary tree containing integers, print the columns of the tree in order with the nodes in each column printed top-to-bottom.
- takepwn February 26, 2016 in United StatesInput: 6 / \ 3 4 / \ \ 5 1 0 / \ / 9 2 8 \ 7 Output: 9 5 3 2 6 1 7 4 8 0 Input: 1 / \ 2 3 / \ / \ 4 5 6 7 When two nodes share the same position (e.g. 5 and 6), they may be printed in either order: Output: 4 2 1 5 6 3 7 or: 4 2 1 6 5 3 7
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Facebook Software Engineer Intern Trees and Graphs - 0of 0 votes
AnswersGiven an array and a number, add it in such a way where array is [0,0,1] and number is 4 output will be [0,0,5]
- Ipalibo February 25, 2016 in United Kingdom
Example 2 :
array is [1] and number is 9 output will be [1,0]| Report Duplicate | Flag | PURGE
Facebook Software Engineer Algorithm - 0of 0 votes
AnswersGiven a set of numbers {x1, x2, x3, x4, ..., xN} (N>=3) a set of its pairwise sums is {x1+x2, x1+x3, x1+x4, x2+x3,x2+x4,x3+x4, ...,}. (That is s_k = x_i + x_j where i != j)
Restore a set of numbers given a set of its pairwise sums.
Note: you don't know given some k, to which i and j it refers, (i.e. input is given in undefined order)
EDIT: couldn't comment, so here is clarification
Example:S = {1, 5, 10, 100} (n elements) P = {6, 11, 101, 15, 105, 110} (n * (n - 1) / 2 elements)
Given P you have to restore S.
Note here means that if you knew which element in P corresponded to which pair of indices in S, you could just solve a simple linear equation
- emb February 22, 2016 in United Statesx1+x2=a{k1} x2+x3 = a{k2}, ...., x{n-1} + x{n} = a{k{n-1}, x{n} + x1 = a{k{n}}
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Facebook Intern - 1of 1 vote
AnswersGiven a string where in each word letters were randomly shuffled and after that words were written without spaces (lets call it X). Also you have a dictionary. The task is to return all possible strings S that can be transformed into the string X and all words in S are from dictionary.
- golyjivan February 19, 2016 in United States| Report Duplicate | Flag | PURGE
Facebook Software Engineer Algorithm - 2of 2 votes
AnswersGiven two arrays/Lists (choose whatever you want to) with sorted and non intersecting intervals. Merge them to get a new sorted non intersecting array/list.
- HumbleLearner February 12, 2016 in United States
Eg:
Given:
Arr1 = [3-11, 17-25, 58-73];
Arr2 = [6-18, 40-47];
Wanted:
Arr3 = [3-25, 40-47, 58-73];| Report Duplicate | Flag | PURGE
Facebook Software Engineer Intern Algorithm - 3of 3 votes
AnswersTask schedule: given a sequence of task like A B C(means 3 different tasks), and a coldtime, which means you need to wait for that much time to start next [same] task. Now----
- songty11 January 27, 2016 in United States
Input: string, n
Output: the best task-finishing sequence.
eg. input: AAABBB, 2
Output: AB_AB_AB
( "_" represents do nothing and wait)| Report Duplicate | Flag | PURGE
Facebook Software Engineer Intern Algorithm - 1of 1 vote
AnswersGiven a decimal number, write a function that returns its negabinary (i.e. negative 2-base) representation as a string.
- JP Ventura January 09, 2016 in United States#!/usr/bin/env python3 assert solution(-15) == '110001' assert solution(2) == '110' assert solution(13) == '11101'
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Facebook Software Engineer / Developer Algorithm - 3of 3 votes
AnswersGiven a forest of balanced binary trees and two nodes, n1 and n2, find the closest common parent of n1 and n2. Nodes have parameters "parent", "left" and "right", and you cannot access the values of the nodes. If n1 and n2 are not on the same tree, return NULL.
- Matt Cooper December 26, 2015 in United States for Software Engineering
Try to do this in O(log(n)) time and O(1) space.| Report Duplicate | Flag | PURGE
Facebook Intern Trees and Graphs - 2of 2 votes
AnswersGiven an undirected graph and a node, modify the graph into a directed graph such that, any path leads to one particular node.
- neer.1304 December 25, 2015 in United States| Report Duplicate | Flag | PURGE
Facebook Software Engineer Algorithm - 1of 1 vote
AnswersGiven integer k and a subset S of set {0, 1, 2, ..., 2^k - 1}
- emb December 13, 2015 in United States
Return the count of pairs (a, b) where a and b are from S and (a < b) and (a & b == a)
& here is bit-wise and.
Do it faster than O((2^k)^2), assume k <= 16
Example:
0b111
0b101
0b010
Answer: 2
0b110
0b011
0b101
Answer: 0| Report Duplicate | Flag | PURGE
Facebook Software Engineer Algorithm - 1of 3 votes
AnswersGiven a random string S and another string T with unique elements, find the minimum consecutive sub-string of S such that it contains all the elements in T.
- Saghar H November 05, 2015 in United States
example:
S='adobecodebanc'
T='abc'
answer='banc'| Report Duplicate | Flag | PURGE
Facebook Software Developer Algorithm - 0of 0 votes
AnswersGiven a set of ranges:
- effy November 02, 2015 in United States
(e.g. S = {(1, 4), (30, 40), (20, 91) ,(8, 10), (6, 7), (3, 9), (9, 12), (11, 14)}.
And given a target range R (e.g. R = (3, 13) - meaning the range going from 3 to 13). Write an algorithm to find the smallest set of ranges that covers your target range. All of the ranges in the set must overlap in order to be considered as spanning the entire target range. (In this example, the answer would be {(3, 9), (9, 12), (11, 14)}.| Report Duplicate | Flag | PURGE
Facebook - 1of 1 vote
AnswersGiven an array of positive integers (excluding zero) and a target number. Detect whether there is a set of consecutive elements in the array that add up to the target.
- m.mirzamo October 28, 2015 in United States
Example: a = {1, 3, 5, 7, 9}
target = 8
output = true ({3, 5})
or target = 15
output = true : {3, 5, 8}
but if target = 6, output would be false. since 1 and 5 are not next to each other.| Report Duplicate | Flag | PURGE
Facebook Intern Algorithm - 0of 0 votes
AnswersGiven an array of integers. Modify the array by moving all the zeros to the end (right side). The order of the other elements doesn't matter.
- m.mirzamo October 28, 2015 in United States| Report Duplicate | Flag | PURGE
Facebook Intern Algorithm Data Structures - 2of 2 votes
AnswersGiven a dictionary containing a list of words, a starting word, and an ending word, return the minimum number of steps to transform the starting word into the ending word.
- ixnay October 28, 2015 in United States
A step involves changing one letter at a time to a valid word that is present in the dictionary.
Return null if it is impossible to transform the starting word into the ending word using the dictionary.
Example:
Starting word: cat
Ending word: dog
cat -> cot -> cog -> dog ('cot' and 'cog' are in the dictionary)
return 3| Report Duplicate | Flag | PURGE
Facebook Software Engineer Algorithm - 2of 2 votes
AnswersGiven predicted stock prices for next n days for a stock e.g : 10, 30, 42, 15, 20, 50, 10, 25 find the maximum profit that can be made with a single buy-sell transaction. If no profit can be made return 0. In the example buying at 15 and selling at 50 gives maximum profit. Note that the two prices are neither minimum nor maximum in the array.
- Kiara October 27, 2015 in United States| Report Duplicate | Flag | PURGE
Facebook Software Engineer / Developer - 4of 4 votes
AnswersWe have an array of objects A and an array of indexes B. Reorder objects in array A with given indexes in array B. Do not change array A's length.
example:
- u-11i24223 October 26, 2015 in United Statesvar A = [C, D, E, F, G]; var B = [3, 0, 4, 1, 2]; sort(A, B); // A is now [D, F, G, C, E];
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Facebook Front-end Software Engineer Front End Web Development - 2of 2 votes
AnswersYou are given a set of points on x axis (consumers)
- emb October 22, 2015 in United States
Also you are given a set of points on a plane (producer)
For every consumer print the nearest producer.
Wanted something better than O(n^2) time.
Example:
consumers: 1 5 7
producers: (0, 3), (1,1), (3, 2), (8, 10), (9, 100)
Answer:
for 1 nearest producer is (1, 1), for 5 nearest is (3, 2), for 7 nearest is (3, 2)
Follow-up question: now both sets are sorted by x coordinate. Could you come up with a linear algorithm?| Report Duplicate | Flag | PURGE
Facebook Software Engineer Algorithm - 0of 0 votes
AnswersGiven n, return 1 ^ 2 ^ 3 ^ ... ^ n
Where ^ is binary xor.
Note: n is a 64-bit number, and 1<<63 is a valid n for this problem.
Examples:
- emb October 07, 2015 in United States>>> reduce(lambda a,b:a^b, [1,2,3]) 0 >>> reduce(lambda a,b:a^b, [1,2,3,4]) 4 >>> reduce(lambda a,b:a^b, [1,2,3,4,5,6,7]) 0 >>> reduce(lambda a,b:a^b, [1,2,3,4,5,6,7,8,9]) 1
| Report Duplicate | Flag | PURGE
Facebook Software Engineer Intern - 0of 0 votes
AnswersGiven an array of positive, unique, increasingly sorted numbers A, e.g. A = [1, 2, 3, 5, 6, 8, 9, 11, 12, 13]. Given a positive value K, e.g. K = 3. Output all pairs in A that differ exactly by K.
- simplysou October 06, 2015 in United States
e.g. 2, 5
3, 6
5, 8
6, 9
8, 11
9, 12
what is the runtime for your code?| Report Duplicate | Flag | PURGE
Facebook Software Developer - 2of 2 votes
AnswersYou are given a permutation arr[N]. E.g. arr[3] = {2, 1, 0} or arr[5] = {0,1,2,4,3};
- emb October 05, 2015 in United States
Then you can prepare somehow and then start serving requests: request(a, b, k) = sorted(arr[a:b])[k], that is, k-th order statistic on slice [a:b] of arr.
E.g. if arr is [3,4,5,0,1,2] and a = 2 and b = 5, then arr[a:b] = [5,0,1] and let k = 2, so we sort it - get [0,1,5] and take k-th element, that is - 5.
Implement request(a, b, k) function. You can preprocess input data, that is, assume there will be only one array and many request() calls.| Report Duplicate | Flag | PURGE
Facebook Software Engineer Algorithm - 3of 3 votes
AnswersDesign Live comments. If your facebook.com homepage is open with bunch of feeds and if someone comments on those feeds, the comments should automatically show up in facebook.com home page without refreshing the page. Feeds could be a simple status update by a friend, post in a group, post by a person you're following, post in a page you've liked etc.
- Rejected September 29, 2015 in United States
Few things what they are looking for -
1. How do you solve it initially and how do you scale it?
2. How do you scale push model in-case if you choose PUSH model to solve it?
3. If push cannot scale how do you solve it?
4. How pull model solves it?
5. When will you use push vs pull?| Report Duplicate | Flag | PURGE
Facebook Software Developer Software Design - 0of 0 votes
AnswersWrite Program for String Permutations using most efficient algorithm. Can you solve problem in O(n) time ?
- dev123 September 23, 2015 in United States| Report Duplicate | Flag | PURGE
Facebook Software Engineer - 0of 0 votes
AnswersConflict resolution in Multi Master systems.
- Kiara September 23, 2015 in United States| Report Duplicate | Flag | PURGE
Facebook Software Engineer / Developer - 2of 2 votes
Answersdesign a URL shortener service
- Kiara September 23, 2015 in United States| Report Duplicate | Flag | PURGE
Facebook Software Engineer / Developer - 1of 1 vote
Answerscheck a binary tree is a binary search tree
- Kiara September 23, 2015 in United States| Report Duplicate | Flag | PURGE
Facebook Software Engineer / Developer - 1of 3 votes
AnswersWrite a function to check if a string matches a regex patter. Note that you only have to deal with patterns containing "*". Also, note that the pattern can't start with "*".
- diwash.timilsina August 04, 2015 in United States
Some examples:
isMatch(“aa”,”a”) → false
isMatch(“aa”,”aa”) → true
isMatch(“aaa”,”aa”) → false
isMatch(“aa”, “a*”) → true
isMatch(“aa”, “*”) → true
isMatch(“ab”, “*”) → true
isMatch(“ab”, “*”) → true
isMatch(“b*a”, “a”) → true
isMatch(“a*a”, “a”) → true
isMatch(“aab”, “c*a*b”) → true| Report Duplicate | Flag | PURGE
Facebook Software Engineer - 3of 3 votes
AnswersGiven an array of integer, find the maximum drop between two array elements, given that second element comes after the first one.
- diwash.timilsina August 04, 2015 in United States| Report Duplicate | Flag | PURGE
Facebook Software Engineer - 1of 3 votes
AnswersOn a given array with N numbers, find subset of size M (exactly M elements) that equal to SUM.
- coredo August 02, 2015 in United States| Report Duplicate | Flag | PURGE
Facebook Software Engineer / Developer Algorithm