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Ibm DSA Interview Questions

178 curated coding interview questions directly asked in Ibm technical rounds, sorted by frequency with recency and difficulty diagnostics.

⚡ Open Interactive Tracker (178 Problems) 🔥 Must-Solve Problem Pool 🏢 All Companies Directory

178 Total Questions

54 (30%) Easy Problems

106 (60%) Medium Problems

18 (10%) Hard Problems

🔥 Most Tested Topics:

Arrays (75)Strings (49)Core DSA (47)Trees (13)Heap (8)

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Showing 178 of 178 displayed

ID	Problem	Difficulty	Topic	Pattern	Acceptance	Frequency	Recency
20	Valid Parentheses	Easy	Strings	Hashing / Sliding Window	44.2%	100.0%	30d
3	Longest Substring Without Repeating Characters	Medium	Strings; Trees	Hashing / Sliding Window; DFS / BFS; Sliding Window	39.1%	100.0%	30d
412	Fizz Buzz	Easy	Core DSA	Implementation / Reasoning	75.5%	100.0%	3m
560	Subarray Sum Equals K	Medium	Arrays	Sorting / Prefix / Scan	47.3%	100.0%	3m
2580	Count Ways to Group Overlapping Ranges	Medium	Core DSA	Implementation / Reasoning	39.1%	87.5%	all
76	Minimum Window Substring	Hard	Arrays; Strings; Trees	Sorting / Prefix / Scan; Hashing / Sliding Window; DFS / BFS; Sliding Window	47.5%	75.0%	6m
3627	Maximum Median Sum of Subsequences of Size 3	Medium	Arrays; Heap	Sorting / Prefix / Scan; Priority Queue	65.1%	75.0%	6m
881	Boats to Save People	Medium	Core DSA	Implementation / Reasoning	61.8%	75.0%	6m
1526	Minimum Number of Increments on Subarrays to Form a Target Array	Hard	Arrays	Sorting / Prefix / Scan	78.2%	75.0%	6m
32	Longest Valid Parentheses	Hard	Strings	Hashing / Sliding Window	38.8%	75.0%	6m
2964	Number of Divisible Triplet Sums	Medium	Arrays	Sorting / Prefix / Scan	67.6%	75.0%	all
1200	Minimum Absolute Difference	Easy	Arrays	Sorting / Prefix / Scan	75.1%	75.0%	all
3107	Minimum Operations to Make Median of Array Equal to K	Medium	Arrays; Heap	Sorting / Prefix / Scan; Priority Queue	47.9%	75.0%	all
3175	Find The First Player to win K Games in a Row	Medium	Core DSA	Implementation / Reasoning	40.3%	75.0%	all
1355	Activity Participants	Medium	Core DSA	Implementation / Reasoning	72.0%	75.0%	all
2602	Minimum Operations to Make All Array Elements Equal	Medium	Arrays	Sorting / Prefix / Scan	38.4%	75.0%	all
453	Minimum Moves to Equal Array Elements	Medium	Arrays	Sorting / Prefix / Scan	58.7%	75.0%	all
12	Integer to Roman	Medium	Strings	Hashing / Sliding Window	71.0%	62.5%	3m
1888	Minimum Number of Flips to Make the Binary String Alternating	Medium	Arrays; Strings	Sorting / Prefix / Scan; Hashing / Sliding Window	53.5%	62.5%	3m
1758	Minimum Changes To Make Alternating Binary String	Easy	Arrays; Strings	Sorting / Prefix / Scan; Hashing / Sliding Window	67.8%	62.5%	3m
647	Palindromic Substrings	Medium	Strings; Trees	Hashing / Sliding Window; DFS / BFS	72.8%	62.5%	3m
1	Two Sum	Easy	Arrays	Sorting / Prefix / Scan; Two Pointers	57.5%	62.5%	3m
72	Edit Distance	Medium	Dynamic Programming	State Transition	60.6%	62.5%	3m
435	Non-overlapping Intervals	Medium	Arrays; Greedy	Sorting / Prefix / Scan; Greedy	57.1%	62.5%	3m
48	Rotate Image	Medium	Arrays	Sorting / Prefix / Scan	80.1%	62.5%	3m
680	Valid Palindrome II	Easy	Strings	Hashing / Sliding Window	44.3%	62.5%	3m
56	Merge Intervals	Medium	Arrays	Sorting / Prefix / Scan	51.8%	62.5%	3m
121	Best Time to Buy and Sell Stock	Easy	Core DSA	Implementation / Reasoning	56.8%	62.5%	3m
13	Roman to Integer	Easy	Strings	Hashing / Sliding Window	66.6%	62.5%	6m
1685	Sum of Absolute Differences in a Sorted Array	Medium	Arrays	Sorting / Prefix / Scan	68.4%	62.5%	6m
17	Letter Combinations of a Phone Number	Medium	Strings; Backtracking	Hashing / Sliding Window; Backtracking	66.1%	62.5%	all
49	Group Anagrams	Medium	Strings	Hashing / Sliding Window	72.6%	62.5%	all
2907	Maximum Profitable Triplets With Increasing Prices I	Medium	Arrays	Sorting / Prefix / Scan	55.9%	62.5%	all
2921	Maximum Profitable Triplets With Increasing Prices II	Hard	Arrays	Sorting / Prefix / Scan	46.1%	62.5%	all
3024	Type of Triangle	Easy	Core DSA	Implementation / Reasoning	44.1%	62.5%	all
3096	Minimum Levels to Gain More Points	Medium	Arrays	Sorting / Prefix / Scan	40.4%	62.5%	all
3147	Taking Maximum Energy From the Mystic Dungeon	Medium	Arrays	Sorting / Prefix / Scan	61.0%	62.5%	all
3145	Find Products of Elements of Big Array	Hard	Arrays	Sorting / Prefix / Scan	24.8%	62.5%	all
2455	Average Value of Even Numbers That Are Divisible by Three	Easy	Core DSA	Implementation / Reasoning	63.2%	62.5%	all
2545	Sort the Students by Their Kth Score	Medium	Arrays; Heap	Sorting / Prefix / Scan; Priority Queue	86.0%	62.5%	all
2562	Find the Array Concatenation Value	Easy	Arrays	Sorting / Prefix / Scan	72.0%	62.5%	all
1710	Maximum Units on a Truck	Easy	Arrays	Sorting / Prefix / Scan	74.9%	62.5%	all
3223	Minimum Length of String After Operations	Medium	Arrays; Strings	Sorting / Prefix / Scan; Hashing / Sliding Window	75.1%	62.5%	all
696	Count Binary Substrings	Easy	Strings; Trees	Hashing / Sliding Window; DFS / BFS	70.4%	62.5%	all
2972	Count the Number of Incremovable Subarrays II	Hard	Arrays	Sorting / Prefix / Scan	40.2%	62.5%	all
1319	Number of Operations to Make Network Connected	Medium	Graphs	BFS / DFS / Topological Sort	66.5%	62.5%	all
2559	Count Vowel Strings in Ranges	Medium	Strings	Hashing / Sliding Window	67.8%	62.5%	all
2734	Lexicographically Smallest String After Substring Operation	Medium	Strings; Trees; Graphs	Hashing / Sliding Window; DFS / BFS; BFS / DFS / Topological Sort	34.9%	62.5%	all
2461	Maximum Sum of Distinct Subarrays With Length K	Medium	Arrays	Sorting / Prefix / Scan	43.0%	62.5%	all
242	Valid Anagram	Easy	Strings	Hashing / Sliding Window	68.1%	62.5%	all
3402	Minimum Operations to Make Columns Strictly Increasing	Easy	Arrays	Sorting / Prefix / Scan	72.7%	62.5%	all
724	Find Pivot Index	Easy	Core DSA	Implementation / Reasoning	62.7%	62.5%	all
845	Longest Mountain in Array	Medium	Arrays	Sorting / Prefix / Scan	42.1%	62.5%	all
1004	Max Consecutive Ones III	Medium	Core DSA	Implementation / Reasoning	67.7%	62.5%	all
1518	Water Bottles	Easy	Core DSA	Implementation / Reasoning	72.6%	62.5%	all
754	Reach a Number	Medium	Core DSA	Implementation / Reasoning	45.1%	62.5%	all
15	3Sum	Medium	Arrays	Sorting / Prefix / Scan	39.1%	50.0%	6m
2405	Optimal Partition of String	Medium	Strings; Dynamic Programming	Hashing / Sliding Window; State Transition	78.4%	50.0%	6m
2193	Minimum Number of Moves to Make Palindrome	Hard	Arrays; Strings	Sorting / Prefix / Scan; Hashing / Sliding Window	52.8%	50.0%	6m
1513	Number of Substrings With Only 1s	Medium	Strings; Trees	Hashing / Sliding Window; DFS / BFS	57.4%	50.0%	6m
42	Trapping Rain Water	Hard	Core DSA	Two Pointers	67.4%	50.0%	6m
9	Palindrome Number	Easy	Strings	Hashing / Sliding Window	60.6%	50.0%	6m
3159	Find Occurrences of an Element in an Array	Medium	Arrays	Sorting / Prefix / Scan	73.4%	50.0%	6m
5	Longest Palindromic Substring	Medium	Strings; Trees	Hashing / Sliding Window; DFS / BFS	37.8%	50.0%	6m
2429	Minimize XOR	Medium	Core DSA	Implementation / Reasoning	62.4%	50.0%	6m
322	Coin Change	Medium	Dynamic Programming	State Transition	48.4%	50.0%	6m
253	Meeting Rooms II	Medium	Greedy	Greedy	52.7%	50.0%	6m
875	Koko Eating Bananas	Medium	Binary Search	Binary Search	50.0%	50.0%	6m
215	Kth Largest Element in an Array	Medium	Arrays; Heap	Sorting / Prefix / Scan; Priority Queue	68.9%	50.0%	6m
146	LRU Cache	Medium	Design	Data Structure Design	47.4%	50.0%	6m
371	Sum of Two Integers	Medium	Arrays	Sorting / Prefix / Scan	55.5%	50.0%	6m
1283	Find the Smallest Divisor Given a Threshold	Medium	Core DSA	Implementation / Reasoning	65.9%	50.0%	6m
2402	Meeting Rooms III	Hard	Greedy	Greedy	51.5%	50.0%	6m
14	Longest Common Prefix	Easy	Core DSA	Implementation / Reasoning	47.6%	50.0%	all
53	Maximum Subarray	Medium	Arrays	Sorting / Prefix / Scan	53.3%	50.0%	all
128	Longest Consecutive Sequence	Medium	Core DSA	Implementation / Reasoning	47.1%	50.0%	all
238	Product of Array Except Self	Medium	Arrays	Sorting / Prefix / Scan	68.9%	50.0%	all
443	String Compression	Medium	Strings	Hashing / Sliding Window	60.0%	50.0%	all
636	Exclusive Time of Functions	Medium	Core DSA	Implementation / Reasoning	66.2%	50.0%	all
98	Validate Binary Search Tree	Medium	Strings; Trees; Binary Search	Hashing / Sliding Window; DFS / BFS; Binary Search	35.8%	50.0%	all
70	Climbing Stairs	Easy	Dynamic Programming	State Transition	54.1%	50.0%	all
844	Backspace String Compare	Easy	Strings	Hashing / Sliding Window	49.9%	50.0%	all
54	Spiral Matrix	Medium	Arrays	Sorting / Prefix / Scan	56.8%	50.0%	all
2950	Number of Divisible Substrings	Medium	Strings; Trees	Hashing / Sliding Window; DFS / BFS	74.6%	50.0%	all
2506	Count Pairs Of Similar Strings	Easy	Strings	Hashing / Sliding Window	73.7%	50.0%	all
2696	Minimum String Length After Removing Substrings	Easy	Arrays; Strings; Trees	Sorting / Prefix / Scan; Hashing / Sliding Window; DFS / BFS	77.2%	50.0%	all
3295	Report Spam Message	Medium	Core DSA	Implementation / Reasoning	48.7%	50.0%	all
2231	Largest Number After Digit Swaps by Parity	Easy	Core DSA	Implementation / Reasoning	65.4%	50.0%	all
1768	Merge Strings Alternately	Easy	Arrays; Strings	Sorting / Prefix / Scan; Hashing / Sliding Window	82.1%	50.0%	all
1051	Height Checker	Easy	Core DSA	Implementation / Reasoning	81.7%	50.0%	all
11	Container With Most Water	Medium	Core DSA	Two Pointers	60.0%	50.0%	all
283	Move Zeroes	Easy	Core DSA	Two Pointers	63.8%	50.0%	all
1167	Minimum Cost to Connect Sticks	Medium	Arrays	Sorting / Prefix / Scan	71.9%	50.0%	all
239	Sliding Window Maximum	Hard	Arrays	Sorting / Prefix / Scan; Sliding Window	48.8%	50.0%	all
4	Median of Two Sorted Arrays	Hard	Arrays; Heap	Sorting / Prefix / Scan; Priority Queue	46.6%	37.5%	all
2904	Shortest and Lexicographically Smallest Beautiful String	Medium	Strings; Graphs	Hashing / Sliding Window; BFS / DFS / Topological Sort	41.1%	37.5%	all
88	Merge Sorted Array	Easy	Arrays	Sorting / Prefix / Scan	54.9%	37.5%	all
169	Majority Element	Easy	Core DSA	Implementation / Reasoning	66.3%	37.5%	all
189	Rotate Array	Medium	Arrays	Sorting / Prefix / Scan	44.9%	37.5%	all
1208	Get Equal Substrings Within Budget	Medium	Strings; Trees	Hashing / Sliding Window; DFS / BFS	59.7%	37.5%	all
2432	The Employee That Worked on the Longest Task	Easy	Core DSA	Implementation / Reasoning	51.7%	37.5%	all
1395	Count Number of Teams	Medium	Core DSA	Implementation / Reasoning	70.2%	37.5%	all
2598	Smallest Missing Non-negative Integer After Operations	Medium	Arrays	Sorting / Prefix / Scan	56.0%	37.5%	all
1834	Single-Threaded CPU	Medium	Core DSA	Implementation / Reasoning	47.7%	37.5%	all
78	Subsets	Medium	Backtracking	Backtracking	82.3%	37.5%	all
153	Find Minimum in Rotated Sorted Array	Medium	Arrays; Binary Search	Sorting / Prefix / Scan; Binary Search	54.7%	37.5%	all
832	Flipping an Image	Easy	Core DSA	Implementation / Reasoning	83.7%	37.5%	all
51	N-Queens	Hard	Backtracking	Backtracking	75.5%	37.5%	all
926	Flip String to Monotone Increasing	Medium	Strings	Hashing / Sliding Window	61.9%	37.5%	all
2587	Rearrange Array to Maximize Prefix Score	Medium	Arrays	Sorting / Prefix / Scan	42.8%	37.5%	all
2134	Minimum Swaps to Group All 1's Together II	Medium	Arrays	Sorting / Prefix / Scan	65.6%	37.5%	all
3130	Find All Possible Stable Binary Arrays II	Hard	Arrays	Sorting / Prefix / Scan	58.9%	37.5%	all
2451	Odd String Difference	Easy	Strings	Hashing / Sliding Window	62.0%	37.5%	all
2390	Removing Stars From a String	Medium	Strings	Hashing / Sliding Window	79.3%	37.5%	all
2406	Divide Intervals Into Minimum Number of Groups	Medium	Arrays	Sorting / Prefix / Scan	63.6%	37.5%	all
268	Missing Number	Easy	Arrays	Sorting / Prefix / Scan	72.0%	37.5%	all
1974	Minimum Time to Type Word Using Special Typewriter	Easy	Arrays; Strings	Sorting / Prefix / Scan; Hashing / Sliding Window	78.7%	37.5%	all
2038	Remove Colored Pieces if Both Neighbors are the Same Color	Medium	Core DSA	Implementation / Reasoning	63.1%	37.5%	all
259	3Sum Smaller	Medium	Arrays	Sorting / Prefix / Scan	51.4%	37.5%	all
1910	Remove All Occurrences of a Substring	Medium	Strings; Trees	Hashing / Sliding Window; DFS / BFS	78.5%	37.5%	all
210	Course Schedule II	Medium	Graphs	BFS / DFS / Topological Sort	55.5%	37.5%	all
767	Reorganize String	Medium	Strings	Hashing / Sliding Window	57.1%	37.5%	all
2948	Make Lexicographically Smallest Array by Swapping Elements	Medium	Arrays; Graphs	Sorting / Prefix / Scan; BFS / DFS / Topological Sort	60.3%	37.5%	all
200	Number of Islands	Medium	Graphs	BFS / DFS / Topological Sort	64.4%	37.5%	all
1752	Check if Array Is Sorted and Rotated	Easy	Arrays; Binary Search	Sorting / Prefix / Scan; Binary Search	57.3%	37.5%	all
1539	Kth Missing Positive Number	Easy	Arrays; Heap	Sorting / Prefix / Scan; Priority Queue	63.5%	37.5%	all
7	Reverse Integer	Medium	Core DSA	Implementation / Reasoning	31.9%	37.5%	all
206	Reverse Linked List	Easy	Linked List	Two Pointers	80.6%	37.5%	all
451	Sort Characters By Frequency	Medium	Arrays; Strings	Sorting / Prefix / Scan; Hashing / Sliding Window	75.3%	37.5%	all
1413	Minimum Value to Get Positive Step by Step Sum	Easy	Arrays	Sorting / Prefix / Scan	64.7%	37.5%	all
217	Contains Duplicate	Easy	Arrays	Sorting / Prefix / Scan	64.4%	37.5%	all
89	Gray Code	Medium	Core DSA	Implementation / Reasoning	64.9%	37.5%	all
151	Reverse Words in a String	Medium	Strings	Hashing / Sliding Window	56.4%	37.5%	all
66	Plus One	Easy	Core DSA	Implementation / Reasoning	50.0%	37.5%	all
67	Add Binary	Easy	Core DSA	Implementation / Reasoning	58.1%	37.5%	all
135	Candy	Hard	Core DSA	Implementation / Reasoning	48.5%	37.5%	all
901	Online Stock Span	Medium	Core DSA	Implementation / Reasoning	69.1%	37.5%	all
33	Search in Rotated Sorted Array	Medium	Arrays; Binary Search	Sorting / Prefix / Scan; Binary Search	44.9%	37.5%	all
141	Linked List Cycle	Easy	Linked List	Two Pointers	54.3%	37.5%	all
350	Intersection of Two Arrays II	Easy	Arrays	Sorting / Prefix / Scan	59.9%	37.5%	all
79	Word Search	Medium	Strings; Binary Search	Hashing / Sliding Window; Binary Search	47.4%	37.5%	all
1963	Minimum Number of Swaps to Make the String Balanced	Medium	Arrays; Strings	Sorting / Prefix / Scan; Hashing / Sliding Window	78.0%	37.5%	all
1163	Last Substring in Lexicographical Order	Hard	Strings; Trees; Graphs	Hashing / Sliding Window; DFS / BFS; BFS / DFS / Topological Sort	35.0%	37.5%	all
921	Minimum Add to Make Parentheses Valid	Medium	Arrays; Strings	Sorting / Prefix / Scan; Hashing / Sliding Window	74.4%	37.5%	all
35	Search Insert Position	Easy	Binary Search	Binary Search	51.3%	37.5%	all
45	Jump Game II	Medium	Greedy	Greedy	42.9%	37.5%	all
475	Heaters	Medium	Core DSA	Implementation / Reasoning	41.9%	37.5%	all
1052	Grumpy Bookstore Owner	Medium	Core DSA	Implementation / Reasoning	64.0%	37.5%	all
23	Merge k Sorted Lists	Hard	Arrays; Linked List; Heap	Sorting / Prefix / Scan; Two Pointers; Priority Queue	59.6%	37.5%	all
1802	Maximum Value at a Given Index in a Bounded Array	Medium	Arrays	Sorting / Prefix / Scan	38.9%	37.5%	all
1604	Alert Using Same Key-Card Three or More Times in a One Hour Period	Medium	Core DSA	Implementation / Reasoning	46.3%	37.5%	all
876	Middle of the Linked List	Easy	Linked List	Two Pointers	81.8%	37.5%	all
26	Remove Duplicates from Sorted Array	Easy	Arrays	Sorting / Prefix / Scan; Two Pointers	62.8%	37.5%	all
155	Min Stack	Medium	Stack / Queue	Monotonic Stack / Simulation	58.2%	37.5%	all
31	Next Permutation	Medium	Backtracking	Backtracking	45.3%	37.5%	all
735	Asteroid Collision	Medium	Core DSA	Implementation / Reasoning	47.9%	37.5%	all
2220	Minimum Bit Flips to Convert Number	Easy	Arrays	Sorting / Prefix / Scan	87.9%	37.5%	all
994	Rotting Oranges	Medium	Core DSA	Implementation / Reasoning	58.7%	37.5%	all
1046	Last Stone Weight	Easy	Core DSA	Implementation / Reasoning	66.5%	37.5%	all
71	Simplify Path	Medium	Core DSA	Implementation / Reasoning	50.6%	37.5%	all
387	First Unique Character in a String	Easy	Strings	Hashing / Sliding Window	65.5%	37.5%	all
1877	Minimize Maximum Pair Sum in Array	Medium	Arrays	Sorting / Prefix / Scan	83.3%	37.5%	all
2	Add Two Numbers	Medium	Core DSA	Implementation / Reasoning	48.5%	37.5%	all
2273	Find Resultant Array After Removing Anagrams	Easy	Arrays; Strings	Sorting / Prefix / Scan; Hashing / Sliding Window	69.9%	37.5%	all
1312	Minimum Insertion Steps to Make a String Palindrome	Hard	Arrays; Strings	Sorting / Prefix / Scan; Hashing / Sliding Window	73.9%	37.5%	all
763	Partition Labels	Medium	Dynamic Programming	State Transition	81.9%	37.5%	all
22	Generate Parentheses	Medium	Strings	Hashing / Sliding Window	78.7%	37.5%	all
485	Max Consecutive Ones	Easy	Core DSA	Implementation / Reasoning	65.2%	37.5%	all
3521	Find Product Recommendation Pairs	Medium	Arrays	Sorting / Prefix / Scan	61.9%	37.5%	all
992	Subarrays with K Different Integers	Hard	Arrays	Sorting / Prefix / Scan	68.1%	37.5%	all
75	Sort Colors	Medium	Arrays	Sorting / Prefix / Scan	69.6%	37.5%	all
152	Maximum Product Subarray	Medium	Arrays	Sorting / Prefix / Scan	36.4%	37.5%	all
1838	Frequency of the Most Frequent Element	Medium	Core DSA	Implementation / Reasoning	44.8%	37.5%	all
191	Number of 1 Bits	Easy	Core DSA	Implementation / Reasoning	76.8%	37.5%	all
2116	Check if a Parentheses String Can Be Valid	Medium	Strings	Hashing / Sliding Window	45.2%	37.5%	all
202	Happy Number	Easy	Core DSA	Implementation / Reasoning	59.7%	37.5%	all
347	Top K Frequent Elements	Medium	Heap	Priority Queue	66.4%	37.5%	all
941	Valid Mountain Array	Easy	Arrays; Strings	Sorting / Prefix / Scan; Hashing / Sliding Window	35.3%	37.5%	all

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