POTD Solutions

GeeksforGeeks Java Solutions

Java solutions for GeeksforGeeks problems with step-by-step explanations on 179+ problems, plus approach notes and complexity analysis across the full archive.

689

Solved

179

Explained

LeetCode C#Topics Study Guide

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