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Citadel interview questions (all time) · FAANGrind

Citadel

FinanceGlobal All time

Citadel is a global alternative investment firm, and Citadel Securities a leading market maker; both run engineering-heavy trading platforms.

Est. 1990

Problems: 90
Window: All time
Topics: 6

90 problems

TopicsLinks

1

1.Rank Transform of a Matrix

Hard1 co.

Hard

also at 0 more

2

2.Design Circular Queue

Medium8 co.

Medium

also at 7 more

3

3.Group Words by Anagrams

Medium35 co.

Medium

also at 34 more

4

4.Best Position for a Service Centre

Hard1 co.

Hard

also at 0 more

5

5.Next Permutation

Medium32 co.

Medium

also at 31 more

6

6.Meeting Scheduler

Medium9 co.

Medium

Greedy Algorithms

also at 8 more

7

Medium2 co.

Medium

Dynamic Programming

also at 1 more

8

8.Number of Ways to Paint N × 3 Grid

Hard2 co.

Hard

also at 1 more

9

9.Knight Probability in Chessboard

Medium2 co.

Medium

Dynamic Programming

also at 1 more

10

10.Sort Items by Groups Respecting Dependencies

Hard1 co.

Hard

also at 0 more

11

11.Moving Average from Data Stream

Easy2 co.

Easy

also at 1 more

12

12.Best time to buy and sell stock

Medium45 co.

Medium

Dynamic Programming

also at 44 more

13

13.Couples Holding Hands

Hard1 co.

Hard

also at 0 more

14

14.Check if a tree is a BST or not

Medium18 co.

Medium

also at 17 more

15

Hard28 co.

Hard

Hashing Linked List

also at 27 more

16

Medium27 co.

Medium

Recursion & Backtracking

also at 26 more

17

17.Design Tic-Tac-Toe

Medium6 co.

Medium

also at 5 more

18

18.Course Schedule I

Medium27 co.

Medium

also at 26 more

19

Easy9 co.

Easy

also at 8 more

20

20.Maximum Length of Repeated Subarray

Medium2 co.

Medium

Dynamic Programming

also at 1 more

21

21.Minimum Costs Using the Train Line

Hard1 co.

Hard

Dynamic Programming

also at 0 more

22

22.Time Based Key-Value Store

Medium15 co.

Medium

also at 14 more

23

23.Insert Delete GetRandom O(1)

Medium20 co.

Medium

also at 19 more

24

24.Sudoku Solver

Hard16 co.

Hard

Recursion & Backtracking

also at 15 more

25

25.Number of Orders in the Backlog

Medium1 co.

Medium

also at 0 more

26

26.Search Suggestions System

Medium9 co.

Medium

also at 8 more

27

27.Transform to Chessboard

Hard1 co.

Hard

Bit Manipulation

also at 0 more

28

28.Find eventual safe states

Medium6 co.

Medium

also at 5 more

29

29.Longest Palindromic Substring

Medium40 co.

Medium

Strings Dynamic Programming

also at 39 more

30

30.Merge Intervals

Medium51 co.

Medium

Greedy Algorithms

also at 50 more

31

31.Find the Duplicate Number

Medium16 co.

Medium

Arrays Bit Manipulation

also at 15 more

32

32.String to Integer (atoi)

Medium15 co.

Medium

also at 14 more

33

33.Trapping Rainwater

Medium48 co.

Medium

also at 47 more

34

34.Letter Combinations of a Phone Number

Medium34 co.

Medium

Recursion & Backtracking

also at 33 more

35

35.Maximum Total Damage With Spell Casting

Medium2 co.

Medium

Dynamic Programming

also at 1 more

36

Easy58 co.

Easy

also at 57 more

37

37.Best time to buy and sell stock with transaction fees

Medium12 co.

Medium

Dynamic Programming

also at 11 more

38

38.Perfect Squares

Medium8 co.

Medium

also at 7 more

39

39.Course Schedule II

Medium26 co.

Medium

also at 25 more

40

40.Meeting Rooms II

Medium26 co.

Medium

Greedy Algorithms

also at 25 more

41

41.Maximal Square

Medium12 co.

Medium

Dynamic Programming

also at 11 more

42

42.Reconstruct Itinerary

Hard11 co.

Hard

also at 10 more

43

43.Best time to buy and sell stock III

Medium13 co.

Medium

Dynamic Programming

also at 12 more

44

44.Maximum path sum

Hard18 co.

Hard

also at 17 more

45

45.Trie Implementation and Advanced Operations

Medium20 co.

Medium

also at 19 more

46

46.Design Search Autocomplete System

Hard7 co.

Hard

also at 6 more

47

47.Length of Longest Subarray With at Most K Frequency

Medium4 co.

Medium

also at 3 more

48

48.Count Number of Maximum Bitwise-OR Subsets

Medium1 co.

Medium

Recursion & Backtracking

also at 0 more

49

49.Reverse Words in a String

Medium14 co.

Medium

also at 13 more

50

50.Implement Min Stack

Medium27 co.

Medium

also at 26 more

Showing 1–50 of 90

Difficulty split

Easy3(3%)
Medium63(70%)
Hard24(27%)

Top topics

Dynamic Programming16
Graphs15
Recursion & Backtracking7
Heaps6
Stack & Queues5
Arrays5