POTD Solutions

GeeksforGeeks Java Solutions

Java solutions for GeeksforGeeks problems with step-by-step explanations on 143+ problems, plus approach notes and complexity analysis across the full archive.

652

Solved

143

Explained

LeetCode C#Topics Study Guide

652 problemsFull explanation available

#	Title
1	0 - 1 Knapsack Problem
2	1s Surrounded by 0s
3	2D Difference Array
4	2D Submatrix Sum Queries
5	Activity Selection
6	Add 1 to a Linked List Number
7	Add Binary Strings
8	Add Number Linked Lists
9	Aggressive Cows
10	Alien Dictionary
11	All numbers with specific difference
12	All Subsets Xor Sum
13	All Unique Permutations of an array
14	Allocate Minimum Pages
15	Alternate positive and negative numbers
16	Alternative Sorting
17	Anagram
18	Anagram Palindrome
19	Ancestors in Binary Tree
20	AND In Range
21	Array Duplicates
22	Array to BST
23	Articulation Point - II
24	ASCII Range Sum
25	Assign Mice Holes
26	Balancing Consonants and Vowels Ratio
27	Bellman-Ford
28	BFS of graph
29	Binary Searchable Count
30	Binary Strings with Equal Sum of Two Halves
31	Binary Tree to DLL
32	Bitonic Point
33	Boolean Parenthesization
34	Bottom View of Binary Tree
35	Brackets in Matrix Chain Multiplication
36	Bridge edge in a graph
37	BST to greater sum tree
38	BST with Dead End
39	Buildings with Sunlight
40	Burning Tree
41	Bus Conductor
42	Bus Ticket Change
43	Buy Stock with Transaction Fee
44	Candy
45	Case-specific Sorting of Strings
46	Check for BST
47	Check for Power
48	Check if a String is Subsequence of Other
49	Check if All Bits Set
50	Check if an Array is Max Heap
51	Check if frequencies can be equal
52	Check if subtree
53	Check If two Line segments Intersect
54	Check Preorder of BST
55	Check Repeated Substring with K Replacements
56	Check Subset sum divisible by k
57	Chocolate Distribution Problem
58	Chocolate Pickup II
59	Chocolates Pickup
60	Choose and Swap
61	Circle of strings
62	Clone a linked list with next and random pointer
63	Clone an Undirected Graph
64	Clone List with Next and Random
65	Closest Neighbour in BST
66	Closest Three Sum
67	Coin Change (Count Ways)
68	Coin Change (Minimum Coins)
69	Coin Piles
70	Common in 3 Sorted Arrays
71	Compare two fractions
72	Consecutive 1's not allowed
73	Construct a Full Binary Tree
74	Construct an array from its pair-sum array
75	Construct Binary Tree from Parent Array
76	Construct List using XOR Queries
77	Construct Tree from Inorder & Preorder
78	Construct Tree from Preorder & Postorder
79	Container With Most Water
80	Count all triplets with given sum in sorted array
81	Count Derangements
82	Count distinct elements in every window
83	Count elements less than or equal to k in a sorted rotated array
84	Count increasing Subarrays
85	Count Indices to Balance Even and Odd Sums
86	Count Inversions
87	Count Linked List Nodes
88	Count Matching Subsequences
89	Count Numbers Containing Specific Digits
90	Count of distinct substrings
91	Count Pairs Divisible By K
92	Count pairs Sum in matrices
93	Count Pairs whose sum is less than target
94	Count pairs with given sum
95	Count Reverse Pairs
96	Count set bits
97	Count Smaller elements
98	Count Sorted Digit Groupings
99	Count Spanning Trees in a Graph
100	Count Subarray with k odds
101	Count Subarrays with given XOR
102	Count Subset With Target Sum II
103	Count the Coprimes
104	Count the number of possible triangles
105	Count the paths
106	Count Unique Vowel Strings
107	Count ways to N'th Stair(Order does not matter)
108	Count X in Range of a Sorted Array
109	Counting elements in two arrays
110	Course Schedule I
111	Course Schedule II
112	Coverage of all Zeros in a Binary Matrix
113	Cut Matrix
114	Cut rope to maximise product
115	Cutting Binary String
116	Decode the string
117	Delete Alternate Nodes
118	Delete node in Doubly Linked List
119	Delete Nodes with Greater on Right
120	Deletion and Reverse in Circular Linked List
121	Design MinMax Queue
122	Detect Loop in linked list
123	DFS of Graph
124	Diameter of a Binary Tree
125	Dice throw
126	Difference Check
127	Dijkstra Algorithm
128	Directed Graph Cycle
129	Distance of nearest cell having 1
130	Distribute Candies
131	Divisible by 13
132	Duplicate Subtrees
133	Edit Distance
134	Elements in range [a, b]
135	Elements in the Range
136	Equal Point in Brackets
137	Equalize All Prefix Sums
138	Equalize the Towers
139	Equilibrium Point
140	Evaluation of Postfix Expression
141	Exactly one swap
142	Exit Point in a Matrix
143	Express as Consecutive Number Sum
144	Expression Add Operators
145	Expression contains redundant bracket or not
146	Extract the Number from the String
147	Facing the sun
148	Farthest Smaller Right
149	Find all possible palindromic partitions of a String
150	Find All Triplets with Zero Sum
151	Find H-Index
152	Find K Smallest Sum Pairs
153	Find Kth Rotation
154	Find length of Loop
155	Find maximum volume of a cuboid
156	Find median in a stream
157	Find Only Repetitive Element from 1 to n-1
158	Find rectangle with corners as 1
159	Find the closest pair from two arrays
160	Find the first node of loop in linked list
161	Find the longest string
162	Find the number of islands
163	Find the Sum of Last N nodes of the Linked List
164	Finding Profession
165	Fixing Two nodes of a BST
166	Flattening a Linked List
167	Flip to Maximize 1s
168	Flood fill Algorithm
169	Floyd Warshall
170	Form a palindrome
171	Form the Largest Number
172	Friends Pairing Problem
173	Frog Jump
174	Game of XOR
175	Game with String
176	Gas Station
177	Generate all binary strings
178	Generate Binary Numbers
179	Generate IP Addresses
180	Generate Permutations of an array
181	Get Min from Stack
182	Get Minimum Squares
183	Gold Mine Problem
184	Graph Diameter
185	Gray Code
186	Group Balls by Sequence
187	Happiest Triplet
188	Height of Binary Tree
189	Histogram Max Rectangular Area
190	Huffman Encoding
191	Identical Linked Lists
192	Implement Atoi
193	Implement k Queues in a Single Array
194	Implement Pow
195	Implement Trie
196	Indexes of Subarray Sum
197	Inorder Traversal
198	Insert in Sorted Circular Linked List
199	Insert in Sorted way in a Sorted DLL
200	Insert Interval
201	Integral Points Inside Triangle
202	Interleave the First Half of the Queue with Second Half
203	Interleaved Strings
204	Intersection in Y Shaped Lists
205	Intersection of Two arrays with Duplicate Elements
206	Intersection of Two Sorted Arrays
207	Intersection Point in Y Shaped Linked Lists
208	Is Binary Tree Heap
209	Is Linked List Length Even
210	Job Sequencing Problem
211	Josephus problem
212	K closest elements
213	K Closest Points to Origin
214	K closest Values
215	k largest elements
216	K Sized Subarray Maximum
217	K Sum Paths
218	k Times Appearing Adjacent Two 1's
219	K-Pangrams
220	K-th element of two Arrays
221	K-th Largest Sum Contiguous Subarray
222	k-th Smallest in BST
223	Kadane's Algorithm
224	Koko Eating Bananas
225	Kth distance
226	Kth element in Matrix
227	Kth Largest in a Stream
228	Kth Missing Positive Number in a Sorted Array
229	Kth Smallest
230	Kth Smallest Number in Multiplication Table
231	Largest BST
232	Largest Divisible Subset
233	Largest number in K swaps
234	Largest number in one swap
235	Largest Pair Sum
236	Largest square formed in a matrix
237	Largest subarray of 0's and 1's
238	Largest Unblocked Submatrix
239	Last Coin in a Game of Alternates
240	Last Digit of a^b
241	Last Moment Before All Ants Fall Out
242	LCM Triplet
243	LCS of three strings
244	Left Rotate Matrix K times
245	Left View of Binary Tree
246	Length of Longest Cycle in a Graph
247	Level Order in spiral form
248	Level order traversal
249	Lexicographically Largest String After Deleting K Characters
250	Lexicographically smallest after removing k
251	Linked List Group Reverse
252	Linked List Matrix
253	Linked list of strings forms a palindrome
254	Longest alternating subsequence
255	Longest Bitonic Subarray
256	Longest Bounded-Difference Subarray
257	Longest Common Increasing Subsequence
258	Longest Common Prefix of Strings
259	Longest Common Subsequence
260	Longest Common Substring
261	Longest Consecutive Subsequence
262	Longest Increasing Subsequence
263	Longest Palindrome in a String
264	Longest Palindromic Subsequence
265	Longest Periodic Proper Prefix
266	Longest Possible Route in a Matrix with Hurdles
267	Longest Prefix Suffix
268	Longest Repeating Character Replacement
269	Longest Span in two Binary Arrays
270	Longest String Chain
271	Longest Subarray Length
272	Longest subarray with Atmost two distinct integers
273	Longest Subarray with Majority Greater than K
274	Longest Subarray with Sum K
275	Longest substring with distinct characters
276	Longest Substring with K Uniques
277	Longest valid Parentheses
278	Look and Say Pattern
279	Lowest Common Ancestor in a BST
280	LRU Cache
281	Majority Element
282	Majority Element II
283	Majority Vote
284	Make array elements unique
285	Make Binary Tree From Linked List
286	Make Matrix Beautiful
287	Make Strings Equal
288	Make the array beautiful
289	Matrix Chain Multiplication
290	Max Absolute Diff of Two Subarrays
291	Max After m Range Increments
292	Max Amount by Selling K Tickets
293	Max Circular Subarray Sum
294	Max DAG Edges
295	Max distance between same elements
296	Max Dot Product with 0 Insertions
297	Max Gap Between Two Same
298	Max min Height
299	Max of min for every window size
300	Max Product Subset
301	Max Profit from Two Machines
302	Max rectangle
303	Max Score from Subarray Mins
304	Max Subarray Sum by Removing At Most One
305	Max sum in the configuration
306	Max Sum Increasing Subsequence
307	Max sum path in two arrays
308	Max Sum Subarray of Size at least K
309	Max Sum Subarray of size K
310	Max Xor Subarray of size K
311	Maximise String Score
312	Maximize Array Value After Rearrangement
313	Maximize median after doing k addition operation
314	Maximize Number of 1's
315	Maximize partitions in a String
316	Maximize The Cut Segments
317	Maximize the minimum difference between k elements
318	Maximum Area Between Bars
319	Maximum Connected group
320	Maximum Difference
321	Maximum Non-Adjacent Nodes Sum
322	Maximum Non-Overlapping Odd Palindrome Sum
323	Maximum number of overlapping Intervals
324	Maximum Number of People Defeated
325	Maximum of minimum for every window size
326	Maximum path sum
327	Maximum path sum from any node
328	Maximum People Visible in a Line
329	Maximum Product Subarray
330	Maximum product subset of an array
331	Maximum Reachable Index Difference
332	Maximum Stone Removal
333	Maximum subarray sum 2
334	Maximum Subset XOR
335	Maximum Sum Combination
336	Maximum sum of elements not part of LIS
337	Maximum sum of Non-adjacent nodes
338	Maximum Sum Problem
339	Maximum sum Rectangle
340	Maximum XOR of two numbers in an array
341	Mean of range in array
342	Median in a row-wise sorted Matrix
343	Median of BST
344	Median of two sorted arrays
345	Meeting Rooms
346	Meeting Rooms III
347	Merge K sorted linked lists
348	Merge Sort for Linked List
349	Merge two BST 's
350	Merge two sorted linked lists
351	Merge Without Extra Space
352	Middle of a Linked List
353	Min Add to Make Parentheses Valid
354	Min Chars to Add for Palindrome
355	Min Cost Climbing Stairs
356	Min Edge Movements to Connect a Graph
357	Min Swaps to Group 1s
358	Minimal Cost
359	Minimize the Heights I
360	Minimize the Heights II
361	Minimum Cost of ropes
362	Minimum Cost Path
363	Minimum cost to connect all houses in a city
364	Minimum Cost to cut a board into squares
365	Minimum Cost to Cut a Stick of length N
366	Minimum Cost to Fill Given Weight
367	Minimum Cost to Merge Stones
368	Minimum days to make M bouquets
369	Minimum Deletions
370	Minimum Deletions to Make Sorted
371	Minimum height roots
372	Minimum Increment or Double Operations to Convert
373	Minimum Insert and Delete to Convert
374	Minimum Jumps
375	Minimum K Consecutive Bit Flips
376	Minimum Multiplications to reach End
377	Minimum number of deletions and insertions
378	Minimum Number of Workers
379	Minimum Operations to Connect Hospitals
380	Minimum Platforms
381	Minimum repeat to make substring
382	Minimum Steps to Halve Sum
383	Minimum sum
384	Minimum Toggle to Partition
385	Minimum Weight Cycle
386	Minimum Window Subsequence
387	Mirror Tree
388	Missing And Repeating
389	Missing Element in Range
390	Missing element of AP
391	Missing in Array
392	Mobile numeric keypad
393	Modify the Array
394	Mother Vertex
395	Mountain Subarray Queries
396	Move All Zeroes to End
397	Multiply two linked lists
398	Multiply two strings
399	N meetings in one room
400	N-Digit Numbers with Increasing Digits
401	N-Queen Problem
402	nCr
403	Nearest multiple of 10
404	Nearly sorted
405	Next element with greater frequency
406	Next Greater Element
407	Next Greater Element in Circular Array
408	Next Permutation
409	Next Smallest Palindrome
410	Nine Divisors
411	Non Repeating Character
412	Non-Attacking Black and White Knights
413	Non-overlapping Intervals
414	Not a subset sum
415	Nth Natural Number
416	Number of BST From Array
417	Number of distinct subsequences
418	Number of occurrence
419	Number of pairs
420	Number of paths in a matrix with k coins
421	Number of Rectangles in a Circle
422	Number of Ways to Arrive at Destination
423	Numbers with Given Digit Sum
424	Occurence of an integer in a Linked List
425	Opposite Sign Pair Reduction
426	Optimal binary search tree
427	Optimal Strategy For A Game
428	Overlapping Intervals
429	Painting the Fence
430	Pair Sum in BST
431	Pair with given sum in a sorted array
432	Pairs with certain difference
433	Pairs with difference k
434	Pairs with Less Than K Diff
435	Palindrome Linked List
436	Palindrome Pairs
437	Palindrome Sentence
438	Palindrome SubStrings
439	Parenthesis Checker
440	Partition Equal Subset Sum
441	Partitions with Given Difference
442	Pascal Triangle
443	Path With Minimum Effort
444	Peak element
445	Permutations of a String
446	Police and Thieves
447	Populate Inorder Successor for all nodes
448	Possible Words From Phone Digits
449	Postfix Evaluation
450	Postorder Traversal
451	Power of k in factorial of n
452	Powerful Integer
453	Predecessor and Successor
454	Prime List
455	Prime Pair with Target Sum
456	Print Anagrams Together
457	Print Bracket Number
458	Print Diagonally
459	Print leaf nodes from preorder traversal of BST
460	Product array puzzle
461	Product Pair
462	Pythagorean Triplet
463	Queue Reversal
464	Quick Sort on Linked List
465	Range LCM Queries
466	Rat in a Maze
467	Rat in a Maze Problem - I
468	Rat Maze With Multiple Jumps
469	Rearrange the Array
470	Remaining String
471	Remove all occurences of duplicates in a linked list
472	Remove BST keys outside given range
473	Remove Duplicates
474	Remove duplicates in array
475	Remove Half Nodes
476	Remove Invalid Parentheses
477	Remove loop in Linked List
478	Remove Spaces
479	Remove the balls
480	Reorganize The Array
481	Replace O's with X's
482	Replace with XOR of Adjacent
483	Reverse a Doubly Linked List
484	Reverse a linked list
485	Reverse an Array
486	Reverse Words
487	Roman Number to Integer
488	Roof Top
489	Root to leaf path sum
490	Root to Leaf Paths
491	Root to leaf paths sum
492	Rotate a Linked List
493	Rotate and delete
494	Rotate Array
495	Rotate by 90 degree
496	Rotate Deque By K
497	Rotten Oranges
498	Row with max 1s
499	Safe States
500	Search for Subarray
501	Search in a Row-Column sorted matrix
502	Search in a row-wise sorted matrix
503	Search in a sorted Matrix
504	Search in an almost Sorted Array
505	Search in fully rotated sorted 2D matrix
506	Search in Rotated Sorted Array
507	Search insert position of K in a sorted array
508	Search Pattern (KMP-Algorithm)
509	Search Pattern (Rabin-Karp Algorithm)
510	Seating Arrangement
511	Second Best Minimum Spanning Tree
512	Second Largest
513	Segregate 0s and 1s
514	Sequences where Adjacent Divide
515	Serialize and deserialize a binary tree
516	Set Matrix Zeroes
517	Set Matrix Zeros
518	Shop in Candy Store
519	Shortest Common Supersequence
520	Shortest Cycle
521	Shortest Path in 1-2 Graph
522	Shortest path in Undirected Graph
523	Shortest Path in Weighted undirected graph
524	Shortest Path Using Atmost One Curved Edge
525	Shortest Unique Prefix for Every Word
526	Single Number
527	Size of Binary Tree
528	Smallest distinct window
529	Smallest Divisor
530	Smallest Non-Zero Number
531	Smallest number
532	Smallest Positive Missing
533	Smallest Positive Missing Number
534	Smallest range in K lists
535	Smallest window containing 0, 1 and 2
536	Smallest window containing all characters
537	Smallest window in a string containing all the characters of another string
538	Solve the Sudoku
539	Sort 0s, 1s and 2s
540	Sort a k sorted doubly linked list
541	Sort a linked list of 0s, 1s and 2s
542	Sort by Absolute Difference
543	Sort in specific order
544	Sort the given array after applying the given equation
545	Sorted and Rotated Minimum
546	Sorted subsequence of size 3
547	Sorting Elements of an Array by Frequency
548	Spirally traversing a matrix
549	Split an array into two equal Sum subarrays
550	Split array in three equal sum subarrays
551	Split Array into Minimum Subsets
552	Split Array Largest Sum
553	Split Array Subsequences
554	Split Linked List Alternatingly
555	Split the Array
556	Square root of a number
557	Stable Marriage Problem
558	Stickler Thief
559	Stickler Thief II
560	Stock Buy and Sell – Max 2 Transactions Allowed
561	Stock Buy and Sell – Max K Transactions Allowed
562	Stock Buy and Sell – Max one Transaction Allowed
563	Stock Buy and Sell – Multiple Transaction Allowed
564	Stock Buy and Sell with Cooldown
565	Stock span problem
566	Stream First Non-repeating
567	String stack
568	Strings Rotations of Each Other
569	Sub-arrays with equal number of occurences
570	Subarray Frequency Count Queries
571	Subarray range with given sum
572	Subarrays With At Most K Distinct Integers
573	Subarrays with First Element Minimum
574	Subarrays with Sum in Range
575	Subarrays with sum K
576	Subset Sum Problem
577	Subset XOR
578	Subsets with Products of Distinct Primes
579	Substring with Max Zero-One Diff
580	Substrings of length k with k-1 distinct elements
581	Substrings with K Distinct
582	Substrings with more 1's than 0's
583	Substrings with same first and last characters
584	Sum of all substrings of a number
585	Sum of Mode
586	Sum of Nodes in BST Range
587	Sum of nodes on the longest path
588	Sum of subarray minimum
589	Sum of subarray minimums
590	Sum of subarray ranges
591	Sum of Subarrays
592	Sum of XOR of all pairs
593	Sum Pair closest to target
594	Sum Tree
595	Sum-string
596	Summed Matrix
597	Swap and Maximize
598	Swap diagonals
599	Swap Kth nodes from ends
600	Symmetric Tree
601	Target Sum
602	The Celebrity Problem
603	The Knight's tour problem
604	The Painter's Partition Problem-II
605	The Palindrome Pattern
606	Toeplitz matrix
607	Top K Frequent in Array
608	Top View of Binary Tree
609	Topological sort
610	Total count
611	Total Decoding Messages
612	Towers Reaching Both Stations
613	Trail of ones
614	Transform to Sum Tree
615	Transpose of Matrix
616	Trapping Rain Water
617	Travelling Salesman Problem
618	Tree Boundary Traversal
619	Triplet Family
620	Two Equal Sum Subarrays
621	Two Smallests in Every Subarray
622	Two Sum - Pair with Given Sum
623	Two Swaps
624	Two water Jug problem
625	Tywin's War Strategy
626	Undirected Graph Cycle
627	Union of Arrays with Duplicates
628	Union of Two Sorted Arrays with Distinct Elements
629	Unique K-Number Sum
630	Unique Number I
631	Unique Number II
632	Unique Number III
633	Unique Paths in a Grid
634	URLify a given string
635	Validate an IP Address
636	Vertical Sum
637	Vertical Tree Traversal
638	Vertical Width of a Binary Tree
639	Walls Coloring II
640	Ways to Express as Sum of Consecutives
641	Ways to Increase LCS by One
642	Ways to Reach the n'th Stair
643	Ways To Tile A Floor
644	Ways to Tile the Floor
645	Weighted Job Scheduling
646	Wifi Range
647	Wildcard Pattern Matching
648	Word Break
649	Word Search
650	XOR Linked List
651	XOR Pairs less than K
652	ZigZag Tree Traversal