POTD Solutions

GeeksforGeeks Java Solutions

Java solutions for GeeksforGeeks problems with step-by-step explanations on 139+ problems, plus approach notes and complexity analysis across the full archive.

648

Solved

139

Explained

LeetCode C#Topics Study Guide

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