Facebook Interview Questions
- -1of 1 vote
AnswersDesign copy-on-write string class
- ajay.raj May 22, 2017 in United States
e.g. stringclass s("abc");
stringclass s1 = s; // no copy
s = "bcd"; // copy| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
AnswerDesign and implement an algorithm to assign an unlimited M number of messages evenly among N number of servers (N will not change).
- aifra2000 May 20, 2017 in United States
Input to the algorithm
A message contains a message identifier and a text string. The algorithm will be fed one message at a time.
There are N numbers of servers (N will not change), each can be identified by a unique id.
Output of the algorithm
When the algorithm is called to process a message, it should output the id of the server that the message is assigned to.| Report Duplicate | Flag | PURGE
Facebook SDE-3 - 0of 0 votes
AnswersGiven an ODD number, print diamond pattern of stars recursively.
n = 5, Diamond shape is as follows: * *** ***** *** *
void print(int n){
- ajay.raj May 20, 2017 in United States
}| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
Answers/From the input array, output a subset array with numbers part of a Fibonacci series.
- ajay.raj May 20, 2017 in United States
// input: [4,2,8,5,20,1,40,13,23]
// output: [2,5,1,8,13]
public static List<Integer> getFibNumbers(int[] nums){}| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
AnswersThe number of valid combinations of a strings for given input array a[], where a=>1, z => 26, and 0 <= a[i] <= 9
- nelly2k May 19, 2017 in United States
{1,1,1} => {aaa, ak, ka} => 3
{1,1,0} => {aj} => 1| Report Duplicate | Flag | PURGE
Facebook SDE-2 Algorithm - 0of 0 votes
AnswersCan multiple threads improve the time complexity to merge k sorted arrays? If so, how?
- ajay.raj May 18, 2017 in United States| Report Duplicate | Flag | PURGE
Facebook SDE1 Arrays - 0of 0 votes
AnswersGives an array of unsorted int (may have negative number),
- ajay.raj May 15, 2017 in United States
rearrange the array such that the
num at the odd index is greater than the num at the even index.
example
giving 5, 2, 3, 4, 1, one of the expected result is 1,4,2,5,3,
please solve it in o(n) time, where n is the length of the array
public void rearrange(int[] nums){
}| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
Answers
- ajay.raj May 15, 2017 in United StatesGiven a string, find all possible combinations of the upper and lower case of each Alphabet char, keep the none Alphabet char as it is. example1 s = "ab", return: "Ab", "ab", "aB", "AB" example2 s = "a1b", return: "A1b", "a1b", "a1B", "A1B" public List<String> getPermutation(String s){ }
| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
AnswersGiven a binary tree of integers, write code to store the tree into a list of integers and recreate the original tree from a list of integers.
- Null0 May 13, 2017
Here's what your method signatures should look like (in Java):
List<Integer> store(Node root)
Node restore(List<Integer> list)
Example Tree:
5
/ \
3 2
/ / \
1 6 1| Report Duplicate | Flag | PURGE
Facebook Software Engineer Algorithm Data Structures Java Trees and Graphs - 0of 0 votes
AnswersFor a given array, find the subarray (containing at least k number) which has the largest sum.
- ajay.raj May 13, 2017 in United States
Example:
// [-4, -2, 1, -3], k = 2, return -1, and the subarray is [-2, 1]
// [1, 1, 1, 1, 1, 1], k = 3, return 6, and the subarray is [1, 1, 1, 1, 1, 1]
try to do it in O(n) time
Followup, if input is stream, how to solve it
public int maxSubArray(int[] nums, int k) {}| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
Answersfind maximum contiguous subarray sum with size (the number of the element in the subarray) <= k
- ajay.raj May 12, 2017 in United States
a brute force method is very simple, can you do it better?
public int maxSum(int[] nums, int k){
}| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
AnswersI want to learn some big words so people think I'm smart.
- Ajibz May 11, 2017 in United States
I opened up a dictionary to a page in the middle and started flipping through, looking for words I didn't know. I put each word I didn't know at increasing indices in a huge array I created in memory. When I reached the end of the dictionary, I started from the beginning and did the same thing until I reached the page I started at.
Now I have an array of words that are mostly alphabetical, except they start somewhere in the middle of the alphabet, reach the end, and then start from the beginning of the alphabet. In other words, this is an alphabetically ordered array that has been "rotated." For example:
String[] words = new String[]{
"ptolemaic",
"retrograde",
"supplant",
"undulate",
"xenoepist",
"asymptote", // <-- rotates here!
"babka",
"banoffee",
"engender",
"karpatka",
"othellolagkage",
};
Write a function for finding the index of the "rotation point," which is where I started working from the beginning of the dictionary. This array is huge (there are lots of words I don't know) so we want to be efficient here.| Report Duplicate | Flag | PURGE
Facebook Development Support Engineer Sorting - 0of 0 votes
Answers// Read4K - Given a function which reads from a file or
- ajay.raj May 11, 2017 in United States
// network stream up to 4k at a time, give a function which
// which can satisfy requests for arbitrary amounts of data
private int read4K(char[] buf) {
// GIVEN
}
// IMPLEMENT:
public int read(char[] buf, int toRead) { }
Due to network latency, if the read4K method return a value < 4k, it does not necessarily mean that we reach the End of File (EOF), in this case, you should continue to read the file until you reach toRead or EOF.| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
Answersgiven a graph: example -> A company holds 10% of B company’s share,
- ajay.raj May 11, 2017 in United States
B company holds 5% of C company’s share, A company holds 2% of C company’s share,
what percent of C company’s share does A company hold?| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
Answers
- ajay.raj May 11, 2017 in United States// Design and implement key value system // // string -> string // Insert a key-value pair or modify a value void put(string key, string value); // Delete a key-value pair void delete(string key); // Gets a value given a snapshot string get(string key, Snapshot snap); // Take a snapshot Snapshot takeSnapshot(); // Delete a snapshot void deleteSnapshot(Snapshot snap); // put(k1,v1) // put(k2,v2) // put(k3,v3) // takeSnapshot -> snap1 { k1 -> v1, k2 -> v2, k3 -> v3 } // get(k1,snap1) -> v1 // put(k1,v4) // delete(k3) // takeSnapshot -> snap2 { k1 -> v4, k2 -> v2 } // get(k1,snap2) -> v4 // get(k1,snap1) -> v1 // get(k3,snap2) -> XX // deleteSnapshot(snap1) // get(k1,snap1) -> XX // Space efficient is more important than time efficient, thus please use as small space as possible.
| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
AnswersInsert node with a given value in a circular sorted linked list.
- sbdul May 10, 2017 in UK| Report Duplicate | Flag | PURGE
Facebook Software Engineer Intern - 0of 0 votes
AnswersGiven list of N points find the K closest points to origin i.e((0,0)).
- sbdul May 10, 2017 in UK| Report Duplicate | Flag | PURGE
Facebook Software Engineer Intern - 0of 0 votes
AnswersGiven a mapping from digits to list of letters and a string of digits of arbitrary length determine all possible ways to replace the digits with letters.
- syam.bollu May 09, 2017 in United States
Input Mapping = {
'1' → ['A', 'B', 'C'],
'2' → ['D', 'E', 'F'],
...
}
Avg length of map values - N
Input String = “12” - K
Expected Output = [“AD”, “AE”, “AF”, “BD”, “BE”, “BF”, “CD”, “CE”, “CF”]| Report Duplicate | Flag | PURGE
Facebook Front End Web Development - 0of 0 votes
AnswersGiven a task sequence tasks such as ABBABBC, and an integer k, which is the cool down time between two same tasks. Assume the execution for each individual task is 1 unit.
- ajay.raj May 08, 2017 in United States
rearrange the task sequence such that the execution time is minimal.
Example:
S = AAABBBCCC, K = 3
Result: ABCABCABC (all 'A's are 3 distance apart, similarly with B's and C's), thus return 9
S = AAABC, K=2
Result: ABCA_ _A, thus return 7
S = AAADBBCC, K = 2:
Result: ABCABCDA, thus return 8
public int rearrangeTasks(String tasks, int cooldown){
}| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
AnswersGiven an array of n elements which contains elements from 0 to n-1, with any of these numbers appearing any number of times. Find these repeating numbers in O(n) and using only constant memory space.
- ajay.raj May 08, 2017 in United States
Try to do it in one pass
example
[4, 2, 0, 5, 2, 0, 1] return: 0, 2
[1, 2, 3, 0, 0, 1, 3, 6, 6,6] return 0, 1, 3, 6
public List<Integer> findRepeat(int nums[]){
}| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
Answersconvert a ternary expression into a Binary tree structure. a?b:c a / \ b c a?b?c:d:e a / \ b e / \ c d class TreeNode{ char val; TreeNode left; TreeNode right; public TreeNode(char val){ this.val = val; } } public TreeNode build(String s){}
try to do it in o(n) time complexity, n is the size of the string
- ajay.raj May 04, 2017 in United States| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
AnswersGroup a list of words so that the same group of words have a common substring, and this common substring is also in the word lists,
- ajay.raj May 04, 2017 in United States
example
[cow "," cold "," an "," co "], return [[" can "," an "], [" cow "," cold "," co "]]
["can", "cow", "cold"], return [["can"], ["cow"], ["cold"]]
["c", "ca", "can"], return [["c", "ca", "can"]]
public List<List<String>> groupWords(String[] s)| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
AnswersEnter a two digit number, find the year closest to this year.
- ajay.raj May 03, 2017 in United States
Example input 99, return 1999;
Input 15, return 2015.
public int getClosestYear(int input){
}| Report Duplicate | Flag | PURGE
Facebook SDE1 - -2of 4 votes
Answersgenerate random number which differs from the number generated last time in the range of [min, max)
- ajay.raj May 01, 2017 in United States
what is the best way to do it?
public int getNumber(int min, int max){
}| Report Duplicate | Flag | PURGE
Facebook SDE1 - 1of 1 vote
AnswersGiven a undirected graph with each node representing a char and a word,
check if the word can be formed by any path of the graph
example
graph:
a--d--o--g--a--c--t
word : dog, return true;
word: cat, return false;
The same letter may not be used more than once.
- ajay.raj May 01, 2017 in United Statesclass Node { char label; List<Node> neighbors; Node(char x) { label = x; neighbors = new ArrayList<>(); } } class Solution { public boolean exist(List<Node> nodes, String word) { } }
| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
AnswersGiven a Binary tree (Not binary Search Tree ), find the inorder successor of a node.
- ajay.raj April 30, 2017 in United Statesclass TreeNode{ TreeNode left; TreeNode right; int val; public TreeNode(int val){ this.val = val; } } public TreeNode inOrderSuccessor(TreeNode root, TreeNode n) {
| Report Duplicate | Flag | PURGE
Facebook SDE1 - 0of 0 votes
AnswersGiven a positive integer n, find the no of integers less than equal to n, whose binary representation doesn't contain consecutive 1s.
- ajay.raj April 30, 2017 in United States
eg:
I/P : 4
O/P: 4 (0,1,2,4 Valid)
public int count(int n){
}| Report Duplicate | Flag | PURGE
Facebook SDE1 - 2of 2 votes
AnswersGiven an input string and a dictionary of words, find out if the input string can be segmented into a space-separated sequence of dictionary words.
- Anon April 29, 2017 in United States
Ex: "bedbathandbeyond" would be "bed bath and beyond" which are all dictionary words.| Report Duplicate | Flag | PURGE
Facebook Software Engineer String Manipulation - 1of 1 vote
AnswersGiven m 0 and n 1, count the total number of permutations where two 1 cannot be adjacent
- ajay.raj April 29, 2017 in United States
public int count(int m, int n){
}| Report Duplicate | Flag | PURGE
Facebook SDE1 - 1of 1 vote
AnswersFind sets of values in array whose sum is equal to some number.
- blumer April 26, 2017 in United States| Report Duplicate | Flag | PURGE
Facebook Research Scientist Algorithm