POTD Solutions

GeeksforGeeks Java Solutions

Java solutions for GeeksforGeeks problems with step-by-step explanations on 185+ problems, plus approach notes and complexity analysis across the full archive.

695

Solved

185

Explained

LeetCode C#Topics Study Guide

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