Uber — DSA Questions

108 problems confirmed in interviews | 423 total tagged

Problem titles link to LeetCode. Interview mention counts are derived from our analysis of public discussion posts.

Priority List (confirmed in interviews)

#	Problem	Difficulty	Tags	Seen	LC
1	Bus Routes	Hard	Graph	12x	LC
2	Longest Continuous Subarray With Absolute Diff Less Tha	Medium	Array / Two Pointers	6x	LC
3	Course Schedule II	Medium	Graph	5x	LC
4	Alien Dictionary	Hard	Graph	4x	LC
5	LRU Cache	Medium	HashMap / Design	4x	LC
6	My Calendar I	Medium	Intervals	4x	LC
7	Merge Intervals	Medium	Array, Sorting	4x	LC
8	Reconstruct Itinerary	Hard	Array, String, Depth-First Search	4x	LC
9	Number of Islands II	Hard	Graph	3x	LC
10	Number of Islands	Medium	Graph	3x	LC
11	Find the Closest Palindrome	Hard	Math, String	3x	LC
12	Word Search II	Hard	Array, String, Backtracking	3x	LC
13	Find Median from Data Stream	Hard	Heap / PQ	3x	LC
14	Task Scheduler	Medium	Heap / PQ	3x	LC
15	First Unique Number	Medium	HashMap / Design	2x	LC
16	Insert Delete GetRandom O(1)	Medium	HashMap / Design	2x	LC
17	Cherry Pickup	Hard	DP	2x	LC
18	Making A Large Island	Hard	Graph	2x	LC
19	Course Schedule	Medium	Graph	2x	LC
20	Evaluate Division	Medium	Graph	2x	LC
21	Group Anagrams	Medium	Array, Hash Table, String	2x	LC
22	Decode Ways	Medium	DP	2x	LC
23	Cheapest Flights Within K Stops	Medium	Graph	2x	LC
24	Dungeon Game	Hard	DP	2x	LC
25	Rotting Oranges	Medium	Graph	2x	LC
26	Minimum Path Sum	Medium	DP	2x	LC
27	Longest Repeating Character Replacement	Medium	Sliding Window	2x	LC
28	Interval List Intersections	Medium	Array, Two Pointers, Sweep Line	2x	LC
29	Maximum Points You Can Obtain from Cards	Medium	Other	2x	LC
30	Furthest Building You Can Reach	Medium	Array, Greedy, Heap (Priority Queue)	2x	LC
31	Merge Sorted Array	?	Other	2x	LC
32	Design Hit Counter	Medium	HashMap / Design	1x	LC
33	Squares of a Sorted Array	Easy	Other	1x	LC
34	Minimum Edge Reversals So Every Node Is Reachable	Hard	Other	1x	LC
35	Word Search	Medium	Backtracking	1x	LC
36	Text Justification	Hard	Array, String, Simulation	1x	LC
37	Best Time to Buy and Sell Stock	Easy	Other	1x	LC
38	Random Pick with Weight	Medium	Array, Math, Binary Search	1x	LC
39	Split Array Largest Sum	Hard	Binary Search	1x	LC
40	Rotating the Box	Medium	Other	1x	LC
41	Count Primes	Medium	Math	1x	LC
42	Minimum Jumps to Reach End via Prime Teleportation	Medium	Other	1x	LC
43	Maximum Profit in Job Scheduling	Hard	DP	1x	LC
44	Water and Jug Problem	Medium	Other	1x	LC
45	String to Integer (atoi)	Medium	String	1x	LC
46	Valid Palindrome	Easy	String	1x	LC
47	Word Break II	Hard	Array, Hash Table, String	1x	LC
48	Walls and Gates	Medium	Other	1x	LC
49	Optimal Account Balancing	Hard	Array, Dynamic Programming, Backtracking	1x	LC
50	Valid Parentheses	Easy	Stack / Queue	1x	LC
51	Find First and Last Position of Element in Sorted Array	Medium	Binary Search	1x	LC
52	Trapping Rain Water	Hard	Array / Two Pointers	1x	LC
53	Move Zeroes	Easy	Other	1x	LC
54	Smallest String With Swaps	Medium	Other	1x	LC
55	Longest Path With Different Adjacent Characters	Hard	Other	1x	LC
56	Remove Duplicates from Sorted Array	Easy	Array / Two Pointers	1x	LC
57	Remove Element	Easy	Other	1x	LC
58	Climbing Stairs	Easy	DP	1x	LC
59	Majority Element	Easy	Array, Hash Table, Divide and Conquer	1x	LC
60	H-Index	Medium	Array, Sorting, Counting Sort	1x	LC
61	Minimum Number of Taps to Open to Water a Garden	Hard	Array, Dynamic Programming, Greedy	1x	LC
62	Task Scheduler II	Medium	Heap / PQ	1x	LC
63	Paint House	Medium	Array, Dynamic Programming	1x	LC
64	Maximum Width Ramp	Medium	Other	1x	LC
65	Shortest Path in a Grid with Obstacles Elimination	Hard	Tree	1x	LC
66	2 Keys Keyboard	Medium	Other	1x	LC
67	Maximum Number of Events That Can Be Attended	Medium	Other	1x	LC
68	Video Stitching	?	Other	1x	LC
69	Minimum Insertions To Balance A Parentheses String	?	Other	1x	LC
70	Longest Happy String	?	Other	1x	LC
71	Remove Invalid Parentheses	Hard	String, Backtracking, Breadth-First Search	1x	LC
72	Find Building Where Alice And Bob Can Meet	?	Other	1x	LC
73	Range Module	Hard	Design, Segment Tree, Ordered Set	1x	LC
74	Largest Component Size by Common Factor	Hard	Array, Hash Table, Math	1x	LC
75	Smallest Value After Replacing With Sum of Prime Factor	Medium	Math, Simulation, Number Theory	1x	LC
76	Rotate Array	?	Other	1x	LC
77	Jump Game	?	Other	1x	LC
78	Find the Index of the First Occurrence in a String	Easy	Two Pointers, String, String Matching	1x	LC
79	Valid Number	?	Other	1x	LC
80	Unique Paths Ii	?	Other	1x	LC

Graph (19 problems)

#	Problem	Difficulty	Tags	Seen	LC
1	Bus Routes	Hard		12x	LC
2	Course Schedule II	Medium		5x	LC
3	Alien Dictionary	Hard		4x	LC
4	Reconstruct Itinerary	Hard	Array, String, Depth-First Search	4x	LC
5	Number of Islands II	Hard		3x	LC
6	Number of Islands	Medium		3x	LC
7	Making A Large Island	Hard		2x	LC
8	Course Schedule	Medium		2x	LC
9	Evaluate Division	Medium		2x	LC
10	Cheapest Flights Within K Stops	Medium		2x	LC
11	Rotting Oranges	Medium		2x	LC
12	Verifying an Alien Dictionary	Easy			LC
13	Clone Graph	Medium			LC
14	Course Schedule IV	Medium			LC
15	Remove Max Number of Edges to Keep Graph Fully Traversa	Hard			LC
16	Pacific Atlantic Water Flow	Medium			LC
17	Is Graph Bipartite?	Medium	Depth-First Search, Breadth-First Search, Union-Find		LC
18	Max Area of Island	Medium			LC
19	Graph Connectivity With Threshold	Hard	Array, Math, Union-Find		LC

DP (17 problems)

#	Problem	Difficulty	Tags	Seen	LC
1	Cherry Pickup	Hard		2x	LC
2	Decode Ways	Medium		2x	LC
3	Dungeon Game	Hard		2x	LC
4	Minimum Path Sum	Medium		2x	LC
5	Maximum Profit in Job Scheduling	Hard		1x	LC
6	Word Break II	Hard	Array, Hash Table, String	1x	LC
7	Climbing Stairs	Easy		1x	LC
8	House Robber III	Medium	Dynamic Programming, Tree, Depth-First Search		LC
9	Word Break	Medium			LC
10	Regular Expression Matching	Hard	String, Dynamic Programming, Recursion		LC
11	One Edit Distance	Medium			LC
12	House Robber	Medium			LC
13	Coin Change	Medium			LC
14	Longest Increasing Path in a Matrix	Hard			LC
15	Longest Increasing Subsequence	Medium			LC
16	House Robber II	Medium			LC
17	Cherry Pickup II	Hard			LC

Tree (33 problems)

#	Problem	Difficulty	Tags	Seen	LC
1	Shortest Path in a Grid with Obstacles Elimination	Hard		1x	LC
2	Count Paths That Can Form a Palindrome in a Tree	Hard	Hash Table, Bit Manipulation, Tree		LC
3	Construct Quad Tree	Medium			LC
4	Kth Smallest Element in a BST	Medium			LC
5	Minimum Window Substring	Hard			LC
6	Maximum Depth of Binary Tree	Easy			LC
7	Serialize and Deserialize Binary Tree	Hard	String, Tree, Depth-First Search		LC
8	Boundary of Binary Tree	Medium			LC
9	Binary Tree Longest Consecutive Sequence II	Medium			LC
10	Delete Node in a BST	Medium	Tree, Binary Search Tree, Binary Tree		LC
11	Binary Tree Right Side View	Medium			LC
12	Implement Trie (Prefix Tree)	Medium			LC
13	Number of Nodes in the Sub-Tree With the Same Label	Medium	Hash Table, Tree, Depth-First Search		LC
14	Number Of Ways To Reconstruct A Tree	Hard	Array, Hash Table, Tree		LC
15	Number of Strings That Appear as Substrings in Word	Easy			LC
16	Create Binary Tree From Descriptions	Medium			LC
17	Longest Substring Without Repeating Characters	Medium			LC
18	Binary Tree Maximum Path Sum	Hard			LC
19	Collect Coins in a Tree	Hard			LC
20	Most Profitable Path in a Tree	Medium			LC
21	Brightest Position on Street	Medium	Array, Sorting, Prefix Sum		LC
22	Longest Palindromic Substring	Medium			LC
23	Validate Binary Search Tree	Medium	Tree, Depth-First Search, Binary Search Tree		LC
24	Maximum Width of Binary Tree	Medium			LC
25	Complete Binary Tree Inserter	Medium			LC
26	Amount of Time for Binary Tree to Be Infected	Medium			LC
27	Construct Binary Tree from Preorder and Inorder Travers	Medium			LC
28	Sum of Distances in Tree	Hard			LC
29	Number of Distinct Substrings in a String	Medium			LC
30	Binary Search Tree Iterator	Medium			LC
31	Find Critical and Pseudo-Critical Edges in Minimum Span	Hard			LC
32	Closest Binary Search Tree Value	Easy	Binary Search, Tree, Depth-First Search		LC
33	Count Binary Substrings	Easy			LC

Array / Two Pointers (20 problems)

#	Problem	Difficulty	Tags	Seen	LC
1	Longest Continuous Subarray With Absolute Diff Less Tha	Medium		6x	LC
2	Trapping Rain Water	Hard		1x	LC
3	Remove Duplicates from Sorted Array	Easy		1x	LC
4	Product of Array Except Self	Medium			LC
5	Two Sum	Easy			LC
6	Count Subarrays With Fixed Bounds	Hard			LC
7	Maximum Subarray Min-Product	Medium			LC
8	K Divisible Elements Subarrays	Medium			LC
9	Container With Most Water	Medium			LC
10	Maximum Subarray	Medium			LC
11	Subarrays with K Different Integers	Hard			LC
12	Count the Number of Good Subarrays	Medium	Array, Hash Table, Sliding Window		LC
13	Length of Longest Subarray With at Most K Frequency	Medium	Array, Hash Table, Sliding Window		LC
14	Subarray Sums Divisible by K	Medium			LC
15	Remove Duplicates from Sorted Array II	Medium			LC
16	Subarray Sum Equals K	Medium			LC
17	Continuous Subarrays	Medium	Array, Queue, Sliding Window		LC
18	Number of Subarrays That Match a Pattern I	Medium			LC
19	Number of Subarrays with Bounded Maximum	Medium			LC
20	Maximum Average Subarray I	Easy			LC

Sliding Window (2 problems)

#	Problem	Difficulty	Tags	Seen	LC	Editorial	Video
1	Longest Repeating Character Replacement	Medium		2x	LC
2	Sliding Window Maximum	Hard	Array, Queue, Sliding Window		LC

Intervals (9 problems)

#	Problem	Difficulty	Tags	Seen	LC
1	My Calendar I	Medium		4x	LC
2	Merge Intervals	Medium	Array, Sorting	4x	LC
3	Interval List Intersections	Medium	Array, Two Pointers, Sweep Line	2x	LC
4	Meeting Rooms II	Medium			LC
5	Meeting Rooms III	Hard			LC
6	Insert Interval	Medium			LC
7	Meeting Rooms	Easy	Array, Sorting		LC
8	Count Integers in Intervals	Hard	Design, Segment Tree, Ordered Set		LC
9	My Calendar II	Medium			LC

Heap / PQ (7 problems)

#	Problem	Difficulty	Seen	LC
1	Find Median from Data Stream	Hard	3x	LC
2	Task Scheduler	Medium	3x	LC
3	Task Scheduler II	Medium	1x	LC
4	Top K Frequent Words	Medium		LC
5	Top K Frequent Elements	Medium		LC
6	Merge k Sorted Lists	Hard		LC
7	Kth Largest Element in an Array	Medium		LC

Stack / Queue (10 problems)

#	Problem	Difficulty	Tags	Seen	LC
1	Valid Parentheses	Easy		1x	LC
2	Basic Calculator II	Medium			LC
3	Basic Calculator	Hard			LC
4	Generate Parentheses	Medium	String, Dynamic Programming, Backtracking		LC
5	Largest Rectangle in Histogram	Hard			LC
6	Min Stack	Medium			LC
7	Asteroid Collision	Medium			LC
8	Longest Valid Parentheses	Hard	String, Dynamic Programming, Stack		LC
9	Valid Parenthesis String	Medium			LC
10	Maximum Frequency Stack	Hard			LC

HashMap / Design (7 problems)

#	Problem	Difficulty	Tags	Seen	LC
1	LRU Cache	Medium		4x	LC
2	First Unique Number	Medium		2x	LC
3	Insert Delete GetRandom O(1)	Medium		2x	LC
4	Group Anagrams	Medium	Array, Hash Table, String	2x	LC
5	Design Hit Counter	Medium		1x	LC
6	Insert Delete GetRandom O(1) - Duplicates allowed	Hard			LC
7	LFU Cache	Hard			LC

Binary Search (5 problems)

#	Problem	Difficulty	Tags	Seen	LC
1	Split Array Largest Sum	Hard		1x	LC
2	Find First and Last Position of Element in Sorted Array	Medium		1x	LC
3	Search in Rotated Sorted Array	Medium			LC
4	Sqrt(x)	Easy	Math, Binary Search		LC
5	Search in Rotated Sorted Array II	Medium	Array, Binary Search		LC

String (13 problems)

#	Problem	Difficulty	Tags	Seen	LC
1	Find the Closest Palindrome	Hard	Math, String	3x	LC
2	Text Justification	Hard	Array, String, Simulation	1x	LC
3	String to Integer (atoi)	Medium		1x	LC
4	Valid Palindrome	Easy		1x	LC
5	Valid Anagram	Easy			LC
6	Shortest Palindrome	Hard			LC
7	Palindrome Permutation	Easy			LC
8	Longest Palindromic Subsequence	Medium	String, Dynamic Programming		LC
9	Construct K Palindrome Strings	Medium			LC
10	Palindrome Number	Easy			LC
11	Count Different Palindromic Subsequences	Hard	String, Dynamic Programming		LC
12	Count Palindromic Subsequences	Hard			LC
13	Valid Palindrome II	Easy	Two Pointers, String, Greedy		LC

Backtracking (11 problems)

#	Problem	Difficulty	Tags	Seen	LC
1	Word Search II	Hard	Array, String, Backtracking	3x	LC
2	Word Search	Medium		1x	LC
3	Letter Combinations of a Phone Number	Medium	Hash Table, String, Backtracking		LC
4	Valid Sudoku	Medium			LC
5	Sudoku Solver	Hard			LC
6	Next Permutation	Medium	Array, Two Pointers		LC
7	Combination Sum	Medium			LC
8	Subsets	Medium	Array, Backtracking, Bit Manipulation		LC
9	Factor Combinations	Medium	Backtracking		LC
10	Permutations	Medium			LC
11	Largest Divisible Subset	Medium			LC

Matrix / Grid (8 problems)

#	Problem	Difficulty	Tags	LC
1	Spiral Matrix	Medium		LC
2	Rotate Image	Medium		LC
3	Match Alphanumerical Pattern in Matrix I	Medium		LC
4	Set Matrix Zeroes	Medium		LC
5	Search a 2D Matrix II	Medium	Array, Binary Search, Divide and Conquer	LC
6	01 Matrix	Medium		LC
7	Spiral Matrix III	Medium	Array, Matrix, Simulation	LC
8	Shortest Path in Binary Matrix	Medium		LC

Linked List (6 problems)

#	Problem	Difficulty	Tags	LC
1	Swap Nodes in Pairs	Medium		LC
2	Reverse Linked List	Easy		LC
3	Remove Zero Sum Consecutive Nodes from Linked List	Medium		LC
4	Add Two Numbers	Medium		LC
5	Linked List Cycle	Easy	Hash Table, Linked List, Two Pointers	LC
6	Linked List Components	Medium		LC

Math (4 problems)

#	Problem	Difficulty	Tags	Seen	LC
1	Count Primes	Medium		1x	LC
2	Minimum Operations to Reduce an Integer to 0	Medium	Dynamic Programming, Greedy, Bit Manipulation		LC
3	Roman to Integer	Easy	Hash Table, Math, String		LC
4	Reverse Integer	Medium			LC