POTD Solutions

GeeksforGeeks Java Solutions

Java solutions for GeeksforGeeks problems with step-by-step explanations on 120+ problems, plus approach notes and complexity analysis across the full archive.

627

Solved

120

Explained

LeetCode C#Topics Study Guide

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