All problems · DSA Java Articles

All 583 problems in sheet order, keyed by TUF ID.

ID	Problem	Difficulty	Section	Sheets
425	Input Output	Easy	Things to Know in C++/Java/Python or any language	A2Z
1211	Cpp Basics	Easy	Things to Know in C++/Java/Python or any language	A2Z
424	If ElseIf	Easy	Things to Know in C++/Java/Python or any language	A2Z
429	Switch Case	Easy	Things to Know in C++/Java/Python or any language	A2Z
2869	What are arrays, strings?	Easy	Things to Know in C++/Java/Python or any language	A2Z
2867	For loops	Easy	Things to Know in C++/Java/Python or any language	A2Z
2868	While loops	Easy	Things to Know in C++/Java/Python or any language	A2Z
2866	Functions (Pass by Reference and Value)	Easy	Things to Know in C++/Java/Python or any language	A2Z
1219	Theory with examples	Easy	Things to Know in C++/Java/Python or any language	A2Z
1216	Easy and Medium	Easy	Build-up Logical Thinking	A2Z
1205	Hard	Easy	Build-up Logical Thinking	A2Z
401	Pattern 1	Easy	Patterns	A2Z
412	Pattern 2	Easy	Patterns	A2Z
416	Pattern 3	Easy	Patterns	A2Z
417	Pattern 4	Easy	Patterns	A2Z
418	Pattern 5	Easy	Patterns	A2Z
419	Pattern 6	Easy	Patterns	A2Z
420	Pattern 7	Easy	Patterns	A2Z
421	Pattern 8	Easy	Patterns	A2Z
422	Pattern 9	Easy	Patterns	A2Z
402	Pattern 10	Easy	Patterns	A2Z
403	Pattern 11	Easy	Patterns	A2Z
404	Pattern 12	Easy	Patterns	A2Z
405	Pattern 13	Easy	Patterns	A2Z
406	Pattern 14	Easy	Patterns	A2Z
407	Pattern 15	Easy	Patterns	A2Z
408	Pattern 16	Easy	Patterns	A2Z
409	Pattern 17	Easy	Patterns	A2Z
410	Pattern 18	Easy	Patterns	A2Z
411	Pattern 19	Easy	Patterns	A2Z
413	Pattern 20	Medium	Patterns	A2Z
414	Pattern 21	Medium	Patterns	A2Z
415	Pattern 22	Medium	Patterns	A2Z
1218	STL	Easy	Learn STL/Java-Collections or similar thing in your \| language	A2Z
1217	Java Collections	Easy	Learn STL/Java-Collections or similar thing in your \| language	A2Z
367	Count all Digits of a Number	Easy	Know Basic Maths	A2Z
376	Reverse a number	Easy	Know Basic Maths	A2Z
374	Palindrome Number	Easy	Know Basic Maths	A2Z B75
372	GCD of Two Numbers	Easy	Know Basic Maths	A2Z
366	Check if the Number is Armstrong	Easy	Know Basic Maths	A2Z
2807	Print all Divisors	Easy	Know Basic Maths	A2Z
365	Check for Prime Number	Easy	Know Basic Maths	A2Z
2401	Understand recursion by print something N times	Easy	Learn Basic Recursion	A2Z
2405	Print name N times using recursion	Easy	Learn Basic Recursion	A2Z
850	Print 1 to N using Recursion	Easy	Learn Basic Recursion	A2Z
852	Print N to 1 using Recursion	Easy	Learn Basic Recursion	A2Z
386	Sum of First N Numbers	Easy	Learn Basic Recursion	A2Z
371	Factorial of a given number	Easy	Learn Basic Recursion	A2Z
342	Reverse an array	Easy	Learn Basic Recursion	A2Z
378	Check if String is Palindrome or Not	Easy	Learn Basic Recursion	A2Z
381	Fibonacci Number	Easy	Learn Basic Recursion	A2Z
1203	Basic Hashing	Easy	Learn Basic Hashing	A2Z
252	Counting Frequencies of Array Elements	Easy	Learn Basic Hashing	A2Z
344	Highest Occurring Element in an Array	Easy	Learn Basic Hashing	A2Z
947	Selection Sort	Easy	Sorting-I	A2Z
943	Bubble Sort	Easy	Sorting-I	A2Z
944	Insertion Sorting	Easy	Sorting-I	A2Z
945	Merge Sorting	Medium	Sorting-II	A2Z
881	Recursive Bubble Sort	Easy	Sorting-II	A2Z
882	Recursive Insertion Sort	Easy	Sorting-II	A2Z
946	Quick Sorting	Easy	Sorting-II	A2Z
38	Largest Element	Easy	Easy	A2Z
43	Second Largest Element	Easy	Easy	A2Z
379	Check if the Array is Sorted II	Easy	Easy	A2Z
2764	Remove duplicates from Sorted array	Easy	Easy	A2Z
40	Left Rotate Array by One	Easy	Easy	A2Z
39	Left Rotate Array by K Places	Easy	Easy	A2Z
46	Move Zeros to End	Easy	Easy	A2Z
41	Linear Search	Easy	Easy	A2Z
48	Union of two sorted arrays	Easy	Easy	A2Z
44	Find missing number	Easy	Easy	A2Z B75
42	Maximum Consecutive Ones	Easy	Easy	A2Z SDE
2793	Find the number that appears once, and other numbers twice.	Medium	Easy	A2Z
2836	Longest subarray with given sum K(positives)	Medium	Easy	A2Z
564	Longest subarray with sum K	Medium	Easy	A2Z
37	Two Sum	Easy	Medium	A2Z SDE B75
2762	Sort an array of 0's 1's and 2's	Medium	Medium	A2Z
22	Majority Element-I	Easy	Medium	A2Z SDE
29	Kadane's Algorithm	Medium	Medium	A2Z SDE
2761	Print subarray with maximum subarray sum (extended version of above problem)	Medium	Medium	A2Z
2798	Stock Buy and Sell	Medium	Medium	A2Z SDE
34	Rearrange array elements by sign	Medium	Medium	A2Z
31	Next Permutation	Medium	Medium	A2Z SDE
30	Leaders in an Array	Medium	Medium	A2Z
2835	Longest Consecutive Sequence in an Array	Medium	Medium	A2Z
911	Set Matrix Zeroes	Medium	Medium	A2Z SDE B75
35	Rotate matrix by 90 degrees	Medium	Medium	A2Z SDE B75
33	Print the matrix in spiral manner	Medium	Medium	A2Z B75
561	Count subarrays with given sum	Medium	Medium	A2Z
813	Pascal's Triangle I	Easy	Hard	A2Z SDE
23	Majority Element-II	Hard	Hard	A2Z SDE
27	3 Sum	Medium	Hard	A2Z SDE B75
28	4 Sum	Medium	Hard	A2Z SDE
605	Largest Subarray with Sum 0	Medium	Hard	A2Z
562	Count subarrays with given xor K	Hard	Hard	A2Z SDE
715	Merge Overlapping Subintervals	Medium	Hard	A2Z SDE
25	Merge two sorted arrays without extra space	Medium	Hard	A2Z SDE
21	Find the repeating and missing number	Hard	Hard	A2Z SDE B75
20	Count Inversions	Hard	Hard	A2Z
26	Reverse Pairs	Hard	Hard	A2Z SDE
24	Maximum Product Subarray in an Array	Hard	Hard	A2Z B75
81	Search X in sorted array	Easy	BS on 1D Arrays	A2Z
80	Lower Bound	Easy	BS on 1D Arrays	A2Z
82	Upper Bound	Easy	BS on 1D Arrays	A2Z
89	Search insert position	Easy	BS on 1D Arrays	A2Z
86	Floor and Ceil in Sorted Array	Easy	BS on 1D Arrays	A2Z
85	First and last occurrence	Easy	BS on 1D Arrays	A2Z
229	Count Occurrences in a Sorted Array	Easy	BS on 1D Arrays	A2Z
87	Search in rotated sorted array-I	Medium	BS on 1D Arrays	A2Z B75
88	Search in rotated sorted array-II	Medium	BS on 1D Arrays	A2Z
83	Find minimum in Rotated Sorted Array	Easy	BS on 1D Arrays	A2Z B75
84	Find out how many times the array is rotated	Easy	BS on 1D Arrays	A2Z
2770	Single element in a Sorted Array	Medium	BS on 1D Arrays	A2Z
75	Find peak element	Medium	BS on 1D Arrays	A2Z
92	Find square root of a number	Medium	BS on Answers	A2Z
91	Find Nth root of a number	Medium	BS on Answers	A2Z
94	Koko eating bananas	Medium	BS on Answers	A2Z
95	Minimum days to make M bouquets	Medium	BS on Answers	A2Z
93	Find the smallest divisor	Medium	BS on Answers	A2Z
161	Capacity to Ship Packages Within D Days	Medium	BS on Answers	A2Z
600	Kth Missing Positive Number	Medium	BS on Answers	A2Z
73	Aggressive Cows	Hard	BS on Answers	A2Z SDE
74	Book Allocation Problem	Hard	BS on Answers	A2Z
79	Split array - largest sum	Hard	BS on Answers	A2Z
805	Painter's Partition	Medium	BS on Answers	A2Z
78	Minimize Max Distance to Gas Station	Hard	BS on Answers	A2Z
77	Median of 2 sorted arrays	Hard	BS on Answers	A2Z SDE
2767	Kth element of 2 sorted arrays	Medium	BS on Answers	A2Z
66	Find row with maximum 1's	Easy	BS on 2D Arrays	A2Z
69	Search in a 2D matrix	Hard	BS on 2D Arrays	A2Z SDE
68	Search in 2D matrix - II	Hard	BS on 2D Arrays	A2Z
65	Find Peak Element - II	Medium	BS on 2D Arrays	A2Z
67	Matrix Median	Hard	BS on 2D Arrays	A2Z SDE
892	Remove Outermost Parentheses	Medium	Basic and Easy String Problems	A2Z
2863	Reverse words in a given string / Palindrome Check	Medium	Basic and Easy String Problems	A2Z
394	Largest Odd Number in a String	Easy	Basic and Easy String Problems	A2Z
395	Longest Common Prefix	Easy	Basic and Easy String Problems	A2Z SDE
393	Isomorphic String	Easy	Basic and Easy String Problems	A2Z
398	Rotate String	Easy	Basic and Easy String Problems	A2Z
2809	Check if two strings are anagram of each other	Easy	Basic and Easy String Problems	A2Z
399	Sort Characters by Frequency	Easy	Medium String Problems	A2Z
674	Maximum Nesting Depth of the Parentheses	Medium	Medium String Problems	A2Z
903	Roman to Integer	Medium	Medium String Problems	A2Z SDE
974	String to Integer (atoi)	Medium	Medium String Problems	A2Z
2394	Count Number of Substrings	Easy	Medium String Problems	A2Z
638	Longest Palindromic Substring	Medium	Medium String Problems	A2Z B75
993	Sum of Beauty of All Substrings	Medium	Medium String Problems	A2Z
984	Reverse every word in a string	Medium	Medium String Problems	A2Z SDE
1237	Introduction to Singly LinkedList	Easy	Learn 1D LinkedList	A2Z
356	Insertion at the head of Linked List	Easy	Learn 1D LinkedList	A2Z
352	Deletion of the head of LL	Easy	Learn 1D LinkedList	A2Z
470	Find the length of the Linked List	Easy	Learn 1D LinkedList	A2Z
905	Search in Linked List	Medium	Learn 1D LinkedList	A2Z
1234	Introduction to Doubly LL	Easy	Learn Doubly LinkedList	A2Z
361	Insert node before head in Doubly Linked List	Easy	Learn Doubly LinkedList	A2Z
348	Delete head of Doubly Linked List	Easy	Learn Doubly LinkedList	A2Z
900	Reverse a Doubly Linked List	Medium	Learn Doubly LinkedList	A2Z
2810	Middle of a LinkedList [TortoiseHare Method]	Easy	Medium Problems of LL	A2Z
2850	Reverse a LinkedList [Iterative]	Medium	Medium Problems of LL	A2Z
627	Reverse a LL	Medium	Medium Problems of LL	A2Z SDE B75
2845	Detect a loop in LL	Medium	Medium Problems of LL	A2Z
2847	Find the starting point in LL	Medium	Medium Problems of LL	A2Z
623	Length of loop in LL	Medium	Medium Problems of LL	A2Z
2844	Check if LL is palindrome or not	Medium	Medium Problems of LL	A2Z
628	Segregate odd and even nodes in Linked List	Medium	Medium Problems of LL	A2Z
2849	Remove Nth node from the back of the LL	Medium	Medium Problems of LL	A2Z
619	Delete the middle node in LL	Medium	Medium Problems of LL	A2Z
616	Sort LL	Hard	Medium Problems of LL	A2Z
629	Sort a Linked List of 0's 1's and 2's	Medium	Medium Problems of LL	A2Z
2846	Find the intersection point of Y LL	Medium	Medium Problems of LL	A2Z
617	Add one to a number represented by LL	Medium	Medium Problems of LL	A2Z
625	Add two numbers in Linked List	Medium	Medium Problems of LL	A2Z
609	Delete all occurrences of a key in DLL	Hard	Medium Problems of DLL	A2Z
452	Find Pairs with Given Sum in Doubly Linked List	Medium	Medium Problems of DLL	A2Z
610	Remove duplicates from sorted DLL	Hard	Medium Problems of DLL	A2Z
2842	Reverse LL in group of given size K	Hard	Hard Problems of LL	A2Z
2843	Rotate a LL	Hard	Hard Problems of LL	A2Z
2841	Flattening of LL	Hard	Hard Problems of LL	A2Z
611	Clone a LL with random and next pointer	Hard	Hard Problems of LL	A2Z SDE
2862	Recursive Implementation of atoi()	Medium	Get a Strong Hold	A2Z
2855	Pow(x, n)	Easy	Get a Strong Hold	A2Z SDE
222	Count Good Numbers	Medium	Get a Strong Hold	A2Z
2858	Sort a stack using recursion	Medium	Get a Strong Hold	A2Z
901	Reverse a Stack	Medium	Get a Strong Hold	A2Z
493	Generate Binary Strings Without Consecutive 1s	Medium	Subsequences Pattern	A2Z
876	Generate Parentheses	Medium	Subsequences Pattern	A2Z
878	Power Set	Medium	Subsequences Pattern	A2Z
2400	Learn All Patterns of Subsequences (Theory)	Easy	Subsequences Pattern	A2Z
880	Count all subsequences with sum K	Easy	Subsequences Pattern	A2Z
879	Check if there exists a subsequence with sum K	Easy	Subsequences Pattern	A2Z
864	Combination Sum	Medium	Subsequences Pattern	A2Z SDE B75
865	Combination Sum II	Medium	Subsequences Pattern	A2Z SDE
867	Subsets I	Medium	Subsequences Pattern	A2Z
868	Subsets II	Medium	Subsequences Pattern	A2Z SDE
866	Combination Sum III	Medium	Subsequences Pattern	A2Z
875	Letter Combinations of a Phone Number	Hard	Subsequences Pattern	A2Z
871	Palindrome partitioning	Hard	Trying out all Combos / Hard	A2Z SDE
874	Word Search	Hard	Trying out all Combos / Hard	A2Z B75
870	N Queen	Hard	Trying out all Combos / Hard	A2Z SDE
872	Rat in a Maze	Hard	Trying out all Combos / Hard	A2Z SDE
4	Word Break	Medium	Trying out all Combos / Hard	A2Z SDE B75
869	M Coloring Problem	Hard	Trying out all Combos / Hard	A2Z SDE
873	Sudoku Solver	Hard	Trying out all Combos / Hard	A2Z SDE
3	Expression Add Operators	Hard	Trying out all Combos / Hard	A2Z
1155	Introduction to Bits and Tricks	Easy	Learn Bit Manipulation	A2Z
177	Check if the i-th bit is Set or Not	Easy	Learn Bit Manipulation	A2Z
171	Check if a Number is Odd or Not	Easy	Learn Bit Manipulation	A2Z
172	Check if a Number is Power of 2 or Not	Easy	Learn Bit Manipulation	A2Z
243	Count the Number of Set Bits	Easy	Learn Bit Manipulation	A2Z
2410	Set/Unset the rightmost unset bit	Easy	Learn Bit Manipulation	A2Z
1005	Swap Two Numbers	Easy	Learn Bit Manipulation	A2Z
140	Divide two numbers without multiplication and division	Medium	Learn Bit Manipulation	A2Z
141	Minimum Bit Flips to Convert Number	Medium	Interview Problems	A2Z
143	Single Number - I	Medium	Interview Problems	A2Z
142	Power Set Bit Manipulation	Medium	Interview Problems	A2Z
146	XOR of numbers in a given range	Medium	Interview Problems	A2Z
145	Single Number - III	Medium	Interview Problems	A2Z
2853	Print Prime Factors of a Number	Hard	Advanced Maths	A2Z
370	Divisors of a Number	Easy	Advanced Maths	A2Z
651	Count primes in range L to R	Hard	Advanced Maths	A2Z
652	Prime factorisation of a Number	Hard	Advanced Maths	A2Z
877	Pow(x,n)	Easy	Advanced Maths	A2Z
390	Implement Stack using Arrays	Easy	Learning	A2Z SDE
387	Implement Queue using Arrays	Easy	Learning	A2Z SDE
392	Implement Stack using Queue	Easy	Learning	A2Z
389	Implement Queue using Stack	Easy	Learning	A2Z SDE
391	Implement stack using Linkedlist	Easy	Learning	A2Z
388	Implement queue using Linkedlist	Easy	Learning	A2Z
966	Balanced Paranthesis	Easy	Learning	A2Z SDE B75
958	Implement Min Stack	Hard	Learning	A2Z SDE
586	Infix to Postfix Conversion	Medium	Prefix, Infix, PostFix Conversion Problems	A2Z
848	Prefix to Infix Conversion	Medium	Prefix, Infix, PostFix Conversion Problems	A2Z
849	Prefix to Postfix Conversion	Medium	Prefix, Infix, PostFix Conversion Problems	A2Z
825	Postfix to Prefix Conversion	Medium	Prefix, Infix, PostFix Conversion Problems	A2Z
824	Postfix to Infix Conversion	Easy	Prefix, Infix, PostFix Conversion Problems	A2Z
587	Infix to Prefix Conversion	Medium	Prefix, Infix, PostFix Conversion Problems	A2Z
968	Next Greater Element	Medium	Monotonic Stack/Queue Problems [VVV. Imp]	A2Z SDE
969	Next Greater Element - 2	Medium	Monotonic Stack/Queue Problems [VVV. Imp]	A2Z
768	Next Smaller Element	Medium	Monotonic Stack/Queue Problems [VVV. Imp]	A2Z SDE
285	Number of Greater Elements to the Right	Easy	Monotonic Stack/Queue Problems [VVV. Imp]	A2Z
965	Trapping Rainwater	Hard	Monotonic Stack/Queue Problems [VVV. Imp]	A2Z SDE
971	Sum of Subarray Minimums	Medium	Monotonic Stack/Queue Problems [VVV. Imp]	A2Z
967	Asteroid Collision	Medium	Monotonic Stack/Queue Problems [VVV. Imp]	A2Z
972	Sum of Subarray Ranges	Medium	Monotonic Stack/Queue Problems [VVV. Imp]	A2Z
970	Remove K Digits	Medium	Monotonic Stack/Queue Problems [VVV. Imp]	A2Z
959	Largest rectangle in a histogram	Hard	Monotonic Stack/Queue Problems [VVV. Imp]	A2Z SDE
962	Maximum Rectangles	Hard	Monotonic Stack/Queue Problems [VVV. Imp]	A2Z
963	Sliding Window Maximum	Hard	Implementation Problems	A2Z SDE
964	Stock span problem	Hard	Implementation Problems	A2Z SDE
957	Celebrity Problem	Hard	Implementation Problems	A2Z SDE
961	LRU Cache	Medium	Implementation Problems	A2Z SDE
960	LFU Cache	Hard	Implementation Problems	A2Z SDE
2857	Longest Substring Without Repeating Characters	Medium	Medium Problems	A2Z B75
930	Max Consecutive Ones III	Medium	Medium Problems	A2Z
926	Fruit Into Baskets	Medium	Medium Problems	A2Z
927	Longest Repeating Character Replacement	Hard	Medium Problems	A2Z B75
923	Binary Subarrays With Sum	Hard	Medium Problems	A2Z
924	Count number of Nice subarrays	Hard	Medium Problems	A2Z
925	Number of Substrings Containing All Three Characters	Hard	Medium Problems	A2Z
922	Maximum Points You Can Obtain from Cards	Medium	Medium Problems	A2Z
928	Longest Substring With At Most K Distinct Characters	Hard	Hard Problems	A2Z
988	Subarrays with K Different Integers	Medium	Hard Problems	A2Z
931	Minimum Window Substring	Hard	Hard Problems	A2Z B75
754	Minimum Window Subsequence	Hard	Hard Problems	A2Z
1223	Heaps (Theory Video)	Easy	Learning	A2Z
576	Implement Min Heap	Medium	Learning	A2Z
571	Check if an array represents a min heap	Medium	Learning	A2Z
572	Convert Min Heap to Max Heap	Medium	Learning	A2Z
578	K-th Largest element in an array	Medium	Medium Problems	A2Z SDE
2840	Kth smallest element in an array [use priority queue]	Medium	Medium Problems	A2Z
2409	Sort K sorted array	Easy	Medium Problems	A2Z
569	Merge K sorted Lists	Hard	Medium Problems	A2Z
898	Replace Elements by Their Rank	Easy	Medium Problems	A2Z
1008	Task Scheduler	Medium	Medium Problems	A2Z
556	Hand of Straights	Medium	Medium Problems	A2Z
565	Design Twitter	Medium	Hard Problems	A2Z
755	Minimum Cost to Connect Sticks	Medium	Hard Problems	A2Z
2838	Kth largest element in a stream of running integers	Hard	Hard Problems	A2Z
568	Maximum Sum Combination	Hard	Hard Problems	A2Z SDE
566	Find Median from Data Stream	Hard	Hard Problems	A2Z SDE B75
1018	Top K Frequent Elements	Medium	Hard Problems	A2Z SDE B75
2834	Assign Cookies	Easy	Easy Problems	A2Z
489	Fractional Knapsack	Medium	Easy Problems	A2Z SDE
543	Lemonade Change	Easy	Easy Problems	A2Z
545	Valid Paranthesis Checker	Hard	Easy Problems	A2Z
549	N meetings in one room	Medium	Medium/Hard	A2Z SDE
542	Jump Game - I	Easy	Medium/Hard	A2Z B75
595	Jump Game II	Medium	Medium/Hard	A2Z
548	Minimum number of platforms required for a railway	Medium	Medium/Hard	A2Z SDE
547	Job sequencing Problem	Medium	Medium/Hard	A2Z SDE
544	Candy	Hard	Medium/Hard	A2Z
551	Shortest Job First	Medium	Medium/Hard	A2Z
2859	Program for Least Recently Used (LRU) Page Replacement Algorithm	Medium	Medium/Hard	A2Z
546	Insert Interval	Medium	Medium/Hard	A2Z B75
712	Merge Intervals	Medium	Medium/Hard	A2Z B75
550	Non-overlapping Intervals	Medium	Medium/Hard	A2Z B75
2865	Introduction to Trees	Easy	Traversals	A2Z
2864	Binary Tree Representation in Java	Easy	Traversals	A2Z
136	Pre, Post, Inorder in one traversal	Easy	Traversals	A2Z SDE
137	Preorder Traversal	Easy	Traversals	A2Z
2785	Inorder Traversal of Binary Tree	Easy	Traversals	A2Z
135	Postorder Traversal	Easy	Traversals	A2Z SDE
134	Level Order Traversal	Easy	Traversals	A2Z SDE B75
2872	Iterative Preorder Traversal of Binary Tree	Easy	Traversals	A2Z
2786	Iterative Inorder Traversal of Binary Tree	Easy	Traversals	A2Z
2788	Post-order Traversal of Binary Tree using 2 stack	Easy	Traversals	A2Z
2787	Post-order Traversal of Binary Tree using 1 stack	Easy	Traversals	A2Z
2789	Preorder, Inorder, and Postorder Traversal in one Traversal	Easy	Traversals	A2Z
131	Maximum Depth in BT	Medium	Medium Problems	A2Z SDE B75
127	Check for balanced binary tree	Medium	Medium Problems	A2Z SDE
130	Diameter of Binary Tree	Easy	Medium Problems	A2Z SDE
132	Maximum path sum	Medium	Medium Problems	A2Z SDE B75
129	Check if two trees are identical or not	Medium	Medium Problems	A2Z SDE B75
126	Zig Zag or Spiral Traversal	Medium	Medium Problems	A2Z SDE
116	Boundary Traversal	Medium	Medium Problems	A2Z SDE
125	Vertical Order Traversal	Medium	Medium Problems	A2Z SDE
124	Top View of BT	Medium	Medium Problems	A2Z SDE
115	Bottom view of BT	Medium	Medium Problems	A2Z SDE
2782	Right/Left View of Binary Tree	Medium	Medium Problems	A2Z
2784	Symmetric Binary Tree	Medium	Medium Problems	A2Z SDE
122	Print root to leaf path in BT	Medium	Hard Problems	A2Z SDE
118	LCA in BT	Hard	Hard Problems	A2Z SDE
119	Maximum Width of BT	Medium	Hard Problems	A2Z SDE
185	Children Sum Property in Binary Tree	Medium	Hard Problems	A2Z SDE
121	Print all nodes at a distance of K in BT	Hard	Hard Problems	A2Z
120	Minimum time taken to burn the BT from a given Node	Hard	Hard Problems	A2Z
117	Count total nodes in a complete BT	Easy	Hard Problems	A2Z
111	Requirements needed to construct a unique BT	Medium	Hard Problems	A2Z
110	Construct a BT from Preorder and Inorder	Hard	Hard Problems	A2Z SDE
2781	Construct the Binary Tree from Postorder and Inorder Traversal	Hard	Hard Problems	A2Z B75
112	Serialize and De-serialize BT	Hard	Hard Problems	A2Z SDE B75
2791	Morris Preorder Traversal of a Binary Tree	Hard	Hard Problems	A2Z
2792	Morris Inorder Traversal of a Binary Tree	Hard	Hard Problems	A2Z
486	Flatten Binary Tree to Linked List	Medium	Hard Problems	A2Z SDE
1153	Introduction to BST	Easy	Concepts	A2Z
2780	Search in a Binary Search Tree	Easy	Concepts	A2Z
2398	Find Min/Max in BST	Easy	Concepts	A2Z
107	Floor and Ceil in a BST	Easy	Practice Problems	A2Z
2778	Floor in a Binary Search Tree	Easy	Practice Problems	A2Z
104	Insert a given node in BST	Medium	Practice Problems	A2Z
102	Delete a node in BST	Medium	Practice Problems	A2Z
105	Kth Smallest and Largest element in BST	Medium	Practice Problems	A2Z SDE
100	Check if a tree is a BST or not	Medium	Practice Problems	A2Z SDE B75
106	LCA in BST	Medium	Practice Problems	A2Z SDE B75
101	Construct a BST from a preorder traversal	Medium	Practice Problems	A2Z SDE
2775	Inorder Successor/Predecessor in BST	Medium	Practice Problems	A2Z
2772	Merge 2 BST's	Hard	Practice Problems	A2Z
2774	Two Sum In BST \| Check if there exists a pair with Sum K	Hard	Practice Problems	A2Z
97	Correct BST with two nodes swapped	Hard	Practice Problems	A2Z
98	Largest BST in Binary Tree	Hard	Practice Problems	A2Z
1222	Introduction to Graph	Easy	Learning	A2Z
2870	Graph Representation \| C++	Easy	Learning	A2Z
2871	Graph Representation \| Java	Easy	Learning	A2Z
528	Connected Components	Medium	Learning	A2Z B75
529	Traversal Techniques	Medium	Learning	A2Z SDE
2831	DFS	Medium	Learning	A2Z SDE
535	Number of provinces	Medium	Problems on BFS/DFS	A2Z
2830	Connected Components Problem in Matrix	Medium	Problems on BFS/DFS	A2Z
536	Rotten Oranges	Medium	Problems on BFS/DFS	A2Z SDE
531	Flood fill algorithm	Medium	Problems on BFS/DFS	A2Z
2817	Cycle Detection in Undirected Graph (bfs)	Hard	Problems on BFS/DFS	A2Z
501	Detect a cycle in an undirected graph	Hard	Problems on BFS/DFS	A2Z
530	Distance of nearest cell having one	Medium	Problems on BFS/DFS	A2Z
537	Surrounded Regions	Medium	Problems on BFS/DFS	A2Z
533	Number of enclaves	Medium	Problems on BFS/DFS	A2Z
509	Word ladder I	Hard	Problems on BFS/DFS	A2Z
510	Word ladder II	Hard	Problems on BFS/DFS	A2Z
534	Number of islands	Medium	Problems on BFS/DFS	A2Z
2813	Bipartite Graph (DFS)	Hard	Problems on BFS/DFS	A2Z
2814	Cycle Detection in Directed Graph (DFS)	Hard	Problems on BFS/DFS	A2Z
2822	Topo Sort	Hard	Topo Sort and Problems	A2Z
502	Topological sort or Kahn's algorithm	Hard	Topo Sort and Problems	A2Z
500	Detect a cycle in a directed graph	Hard	Topo Sort and Problems	A2Z
504	Course Schedule I	Hard	Topo Sort and Problems	A2Z B75
505	Course Schedule II	Medium	Topo Sort and Problems	A2Z
506	Find eventual safe states	Hard	Topo Sort and Problems	A2Z
503	Alien Dictionary	Hard	Topo Sort and Problems	A2Z B75
508	Shortest path in undirected graph with unit weights	Hard	Shortest Path Algorithms and Problems	A2Z
507	Shortest path in DAG	Hard	Shortest Path Algorithms and Problems	A2Z
2827	Djisktra's Algorithm	Hard	Shortest Path Algorithms and Problems	A2Z
2828	Why priority Queue is used in Djisktra's Algorithm	Hard	Shortest Path Algorithms and Problems	A2Z
527	Shortest Distance in a Binary Maze	Hard	Shortest Path Algorithms and Problems	A2Z
525	Path with minimum effort	Hard	Shortest Path Algorithms and Problems	A2Z
519	Cheapest flight within K stops	Hard	Shortest Path Algorithms and Problems	A2Z
764	Network Delay Time	Medium	Shortest Path Algorithms and Problems	A2Z
524	Number of ways to arrive at destination	Hard	Shortest Path Algorithms and Problems	A2Z
523	Minimum multiplications to reach end	Hard	Shortest Path Algorithms and Problems	A2Z
2826	Bellman Ford Algorithm	Hard	Shortest Path Algorithms and Problems	A2Z
522	Floyd warshall algorithm	Hard	Shortest Path Algorithms and Problems	A2Z
521	Find the city with the smallest number of neighbors	Hard	Shortest Path Algorithms and Problems	A2Z
1221	MST theory	Easy	MinimumSpanningTree/Disjoint Set and Problems	A2Z
2825	Prim's Algorithm	Hard	MinimumSpanningTree/Disjoint Set and Problems	A2Z
516	Disjoint Set	Hard	MinimumSpanningTree/Disjoint Set and Problems	A2Z
517	Find the MST weight	Hard	MinimumSpanningTree/Disjoint Set and Problems	A2Z
515	Number of operations to make network connected	Hard	MinimumSpanningTree/Disjoint Set and Problems	A2Z
513	Most stones removed with same row or column	Medium	MinimumSpanningTree/Disjoint Set and Problems	A2Z
511	Accounts merge	Hard	MinimumSpanningTree/Disjoint Set and Problems	A2Z
514	Number of islands II	Hard	MinimumSpanningTree/Disjoint Set and Problems	A2Z
512	Making a large island	Hard	MinimumSpanningTree/Disjoint Set and Problems	A2Z
1006	Swim in Rising Water	Medium	MinimumSpanningTree/Disjoint Set and Problems	A2Z
497	Bridges in graph	Hard	Other Algorithms	A2Z
496	Articulation point in graph	Hard	Other Algorithms	A2Z
498	Kosaraju's algorithm	Hard	Other Algorithms	A2Z
1195	Introduction to DP	Easy	Introduction to DP	A2Z
287	Climbing stairs	Medium	1D DP	A2Z B75
288	Frog Jump	Medium	1D DP	A2Z
289	Frog jump with K distances	Medium	1D DP	A2Z
291	Maximum sum of non adjacent elements	Medium	1D DP	A2Z B75
290	House robber	Medium	1D DP	A2Z B75
292	Ninja's training	Medium	2D/3D DP and DP on Grids	A2Z
2795	Grid Unique Paths : DP on Grids (DP8)	Medium	2D/3D DP and DP on Grids	A2Z
300	Unique paths II	Medium	2D/3D DP and DP on Grids	A2Z
298	Minimum Falling Path Sum	Medium	2D/3D DP and DP on Grids	A2Z
299	Triangle	Medium	2D/3D DP and DP on Grids	A2Z
769	Ninja and his Friends	Medium	2D/3D DP and DP on Grids	A2Z
2804	Subset sum equal to target (DP- 14)	Hard	DP on Subsequences	A2Z
321	Partition equal subset sum	Hard	DP on Subsequences	A2Z
320	Partition a set into two subsets with minimum absolute sum difference	Hard	DP on Subsequences	A2Z
318	Count subsets with sum K	Hard	DP on Subsequences	A2Z
317	Count partitions with given difference	Hard	DP on Subsequences	A2Z
541	Assign Cookies	Easy	DP on Subsequences	A2Z SDE
2802	Minimum Coins (DP - 20)	Hard	DP on Subsequences	A2Z
324	Target sum	Hard	DP on Subsequences	A2Z
2801	Coin Change 2 (DP - 22)	Hard	DP on Subsequences	A2Z
325	Unbounded knapsack	Hard	DP on Subsequences	A2Z
2803	Rod Cutting Problem - (DP - 24)	Hard	DP on Subsequences	A2Z
308	Longest common subsequence	Hard	DP on Strings	A2Z SDE B75
2799	Print Longest Common Subsequence - (DP - 26)	Hard	DP on Strings	A2Z
309	Longest common substring	Hard	DP on Strings	A2Z
310	Longest palindromic subsequence	Hard	DP on Strings	A2Z
2800	Minimum insertions to make string palindrome - DP-29	Hard	DP on Strings	A2Z
311	Minimum insertions or deletions to convert string A to B	Hard	DP on Strings	A2Z
313	Shortest common supersequence	Hard	DP on Strings	A2Z
306	Distinct subsequences	Hard	DP on Strings	A2Z
307	Edit distance	Hard	DP on Strings	A2Z SDE
314	Wildcard matching	Hard	DP on Strings	A2Z
301	Best time to buy and sell stock	Medium	DP on Stocks	A2Z B75
302	Best time to buy and sell stock II	Medium	DP on Stocks	A2Z
303	Best time to buy and sell stock III	Medium	DP on Stocks	A2Z
304	Best time to buy and sell stock IV	Medium	DP on Stocks	A2Z
56	Best Time to Buy and Sell Stock with Cooldown	Medium	DP on Stocks	A2Z
305	Best time to buy and sell stock with transaction fees	Medium	DP on Stocks	A2Z
636	Longest Increasing Subsequence	Medium	DP on LIS	A2Z SDE B75
851	Print Longest Increasing Subsequence	Medium	DP on LIS	A2Z
2851	Longest Increasing Subsequence - (DP-43)	Medium	DP on LIS	A2Z
603	Largest Divisible Subset	Medium	DP on LIS	A2Z
640	Longest String Chain	Medium	DP on LIS	A2Z
633	Longest Bitonic Subsequence	Medium	DP on LIS	A2Z
780	Number of Longest Increasing Subsequences	Medium	DP on LIS	A2Z
327	Matrix chain multiplication	Hard	MCM DP - Partition DP	A2Z SDE
2806	Matrix Chain Multiplication - Bottom-Up - (DP-49)	Hard	MCM DP - Partition DP	A2Z
328	Minimum cost to cut the stick	Hard	MCM DP - Partition DP	A2Z
326	Burst balloons	Hard	MCM DP - Partition DP	A2Z
276	Different Ways to Evaluate a Boolean Expression	Medium	MCM DP - Partition DP	A2Z
329	Palindrome partitioning II	Hard	MCM DP - Partition DP	A2Z
810	Partition Array for Maximum Sum	Medium	MCM DP - Partition DP	A2Z
2860	Maximum Rectangle Area with all 1's - (DP-55)	Hard	DP on Squares	A2Z
2395	Count Square Submatrices with All Ones - (DP-56)	Easy	DP on Squares	A2Z
1028	Trie Implementation and Operations	Hard	Theory	A2Z SDE B75
1027	Trie Implementation and Advanced Operations	Hard	Problems	A2Z SDE B75
1023	Longest Word with All Prefixes	Medium	Problems	A2Z SDE
1026	Number of distinct substrings in a string	Medium	Problems	A2Z SDE
2390	Bit PreRequisites for TRIE Problems	Easy	Problems	A2Z
1024	Maximum XOR of two numbers in an array	Hard	Problems	A2Z SDE
1025	Maximum Xor with an element from an array	Hard	Problems	A2Z SDE
983	Minimum number of bracket reversals to make an expression balanced	Hard	Hard String Problems	A2Z
982	Count and say	Hard	Hard String Problems	A2Z SDE
2399	Hashing In Strings - Theory	Easy	Hard String Problems	A2Z
979	Rabin Karp Algorithm	Hard	Hard String Problems	A2Z SDE
981	Z function	Hard	Hard String Problems	A2Z SDE
977	KMP Algorithm or LPS array	Hard	Hard String Problems	A2Z SDE
980	Shortest Palindrome	Hard	Hard String Problems	A2Z
978	Longest happy prefix	Hard	Hard String Problems	A2Z
231	Count Palindromic Subsequences	Medium	Hard String Problems	A2Z
36	Sort an array of 0's 1's and 2's	Medium	Medium	SDE
465	Find the Duplicate Number	Medium	Medium	SDE
2758	Inversion of Array (Pre-req: Merge Sort)	Hard	Hard	SDE
297	Grid unique paths	Medium	2D/3D DP and DP on Grids	SDE B75
563	Longest Consecutive Sequence in an Array	Medium	Medium	SDE B75
2837	Largest Subarray with K sum	Medium	Easy	SDE
929	Longest Substring Without Repeating Characters	Medium	Medium Problems	SDE
448	Find Middle of Linked List	Easy	Medium Problems of LL	SDE
613	Merge two Sorted Lists	Hard	Medium Problems of LL	SDE B75
626	Remove Nth node from the back of the LL	Medium	Medium Problems of LL	SDE B75
2848	Add two numbers as LinkedList	Medium	Medium Problems of LL	SDE
258	Delete Node in a Linked List O(1)	Medium	Medium Problems of LL	SDE
621	Find the intersection point of Y LL	Medium	Medium Problems of LL	SDE
620	Detect a loop in LL	Medium	Medium Problems of LL	SDE B75
614	Reverse LL in group of given size K	Hard	Hard Problems of LL	SDE
618	Check if LL is palindrome or not	Medium	Medium Problems of LL	SDE
622	Find the starting point in LL	Medium	Medium Problems of LL	SDE
612	Flattening of LL	Hard	Hard Problems of LL	SDE
615	Rotate a LL	Hard	Hard Problems of LL	SDE
47	Remove duplicates from sorted array	Easy	Easy	SDE
319	Minimum coins	Hard	Easy Problems	SDE
2805	Subset Sums	Hard	Subsequences Pattern	SDE
818	Permutation Sequence	Medium	Trying out all Combos / Hard	SDE
821	Permutations of a String	Medium	Trying out all Combos / Hard	SDE
2757	Word Break (print all ways)	Medium	Trying out all Combos / Hard	SDE
2771	The N-th root of an integer	Medium	BS on Answers	SDE
90	Single element in sorted array	Medium	BS on 1D Arrays	SDE
2769	Search element in a sorted and rotated array/ find pivot where it is rotated	Medium	BS on 1D Arrays	SDE
76	Kth element of 2 sorted arrays	Medium	BS on Answers	SDE
2766	Allocate Minimum Number of Pages	Hard	BS on Answers	SDE
575	Implement Max Heap	Medium	Learning	SDE
713	Merge K Sorted Arrays	Medium	Medium Problems	SDE B75
2808	Implement Stack using Queue (using single queue)	Easy	Learning	SDE
936	Sort a Stack	Medium	Learning	SDE
687	Maximum of Minimums for Every Window Size	Medium	Monotonic Stack/Queue Problems [VVV. Imp]	SDE
2852	Longest Palindrome in a string	Medium	Medium String Problems	SDE
2861	Implement ATOI/STRSTR	Medium	Medium String Problems	SDE
312	Minimum insertions to make string palindrome	Hard	Hard String Problems	SDE
400	Valid Anagram	Easy	Basic and Easy String Problems	SDE B75
198	Compare version numbers	Medium	Medium String Problems	SDE
133	Inorder Traversal	Easy	Traversals	SDE
2790	Preorder Traversal	Easy	Traversals	SDE
139	Morris Inorder Traversal	Hard	Hard Problems	SDE
138	Morris Preorder Traversal	Hard	Hard Problems	SDE
123	Right/Left View of BT	Medium	Medium Problems	SDE
109	Construct a BT from Postorder and Inorder	Hard	Hard Problems	SDE
128	Check for symmetrical BTs	Medium	Medium Problems	SDE
823	Populating Next Right Pointers in Each Node	Medium	Medium Problems	SDE
108	Search in BST	Easy	Concepts	SDE
2391	Construct BST from given keys	Easy	Practice Problems	SDE
103	Inorder successor and predecessor in BST	Medium	Practice Problems	SDE
2779	Floor in a BST	Easy	Practice Problems	SDE
2777	Ceil in a BST	Easy	Practice Problems	SDE
2776	Find K-th smallest element in BST	Medium	Practice Problems	SDE B75
99	Two sum in BST	Hard	Practice Problems	SDE
96	BST iterator	Hard	Practice Problems	SDE
2773	Size of the largest BST in a Binary Tree	Hard	Practice Problems	SDE
62	Binary Tree to Doubly Linked List	Medium	Hard Problems	SDE
446	Find Median in a Stream	Medium	Hard Problems	SDE
567	Kth largest element in a stream of running integers	Hard	Hard Problems	SDE
279	Distinct Numbers in Each Subarray	Medium	Medium Problems	SDE
2839	K-th largest element in an unsorted array.	Medium	Medium Problems	SDE
2832	Flood-fill Algorithm	Medium	Problems on BFS/DFS	SDE
188	Clone Graph	Medium	Problems on BFS/DFS	SDE B75
2818	Detect A cycle in Undirected Graph using BFS	Hard	Problems on BFS/DFS	SDE
2819	Detect A cycle in Undirected Graph using DFS	Hard	Problems on BFS/DFS	SDE
2816	Detect A cycle in a Directed Graph using DFS	Hard	Topo Sort and Problems	SDE
2815	Detect A cycle in a Directed Graph using BFS	Hard	Topo Sort and Problems	SDE
2820	Topological Sort BFS	Hard	Topo Sort and Problems	SDE
2821	Topological Sort DFS	Hard	Topo Sort and Problems	SDE
2833	Number of islands(Do in Grid and Graph Both)	Medium	Problems on BFS/DFS	SDE B75
499	Bipartite graph	Hard	Problems on BFS/DFS	SDE
2812	Bipartite Check using DFS	Hard	Problems on BFS/DFS	SDE
2811	Strongly Connected Component(using KosaRaju's algo)	Hard	Other Algorithms	SDE
520	Dijkstra's algorithm	Hard	Shortest Path Algorithms and Problems	SDE
518	Bellman ford algorithm	Hard	Shortest Path Algorithms and Problems	SDE
2829	Floyd Warshall Algorithm	Hard	Shortest Path Algorithms and Problems	SDE
2824	MST using Prim's Algo	Hard	MinimumSpanningTree/Disjoint Set and Problems	SDE
2823	MST using Kruskal's Algo	Hard	MinimumSpanningTree/Disjoint Set and Problems	SDE
2759	Max Product Subarray	Hard	Hard	SDE
315	0 and 1 Knapsack	Hard	DP on Subsequences	SDE
698	Maximum Sum Increasing Subsequence	Medium	DP on LIS	SDE
2797	Minimum sum path in the matrix	Medium	2D/3D DP and DP on Grids	SDE
316	Coin change II	Hard	DP on Subsequences	SDE B75
323	Subset sum equals to target	Hard	DP on Subsequences	SDE
322	Rod cutting problem	Hard	DP on Subsequences	SDE
1004	Super Egg Drop	Medium	MCM DP - Partition DP	SDE
2854	Palindrome Partitioning (MCM Variation)	Hard	MCM DP - Partition DP	SDE
691	Maximum Profit in Job Scheduling	Medium	1D DP	SDE
2856	Power Set (this is very important)	Medium	Subsequences Pattern	SDE
2392	Contains Duplicate	Easy	Easy	B75
2404	Product of Array Except Self	Easy	Medium	B75
2760	Kadane's Algorithm, maximum subarray sum	Medium	Medium	B75
2396	Container with most water	Easy	Medium Problems	B75
2411	Sum of Two Integers	Easy	Interview Problems	B75
2402	Number of 1 Bits	Easy	Interview Problems	B75
2393	Counting Bits	Easy	Interview Problems	B75
2406	Reverse Bits	Easy	Interview Problems	B75
2397	Decode Ways	Easy	1D DP	B75
2403	Pacific Atlantic Water Flow	Easy	Problems on BFS/DFS	B75
495	Graph Valid Tree	Medium	Problems on BFS/DFS	B75
709	Meeting Rooms	Easy	Medium/Hard	B75
710	Meeting Rooms II	Medium	Medium/Hard	B75
2407	Reorder List	Easy	Medium Problems of LL	B75
559	Group Words by Anagrams	Medium	Medium String Problems	B75
2794	Palindromic Substrings	Medium	Medium String Problems	B75
331	Encode and Decode Strings	Medium	Medium String Problems	B75
2783	Invert/Flip Binary Tree (Create)	Medium	Medium Problems	B75
2408	Subtree of Another Tree	Easy	Medium Problems	B75