LeetCode

LeetCode problems and how I solved them.

Structure

• Explore - useful technics shortcuts for learn
• Solutions - all solved and refactored problems
• Again - need resolve because of loosing day streak or not enough knowledge
• Archive - all solved problems that in progress refactoring

Development

After adding some code samples run code.sh

./scripts/code.sh

You can automate this action by calling pre-commit.sh

Testing

./scripts/test.sh

Completed explores

• The LeetCode Beginner's Guide
• Array and String. Introduction to Data Structure
• Top Interview Questions. Easy Collection

Completed problems

#	Problem	Solution
1	Two Sum	twosum_1.go
2	Add Two Numbers	addtwonumbers.go
3	Longest Substring Without Repeating Characters	lengthoflongestsubstring.go
4	Median of Two Sorted Arrays	findmediansortedarrays.go
7	Reverse Integer	reverse.go
9	Palindrome Number	ispalindrome_1.go
19	Remove Nth Node From End of List	removenthfromend.go
35	Search Insert Position	searchinsert.go
49	Group Anagrams	groupanagrams.go
53	Maximum Subarray	maxsubarray.go
57	Insert Interval	insert.go
58	Length of Last Word	lengthoflastword.go
62	Unique Paths	uniquepaths.go
69	Sqrt(x)	mysqrt.go
70	Climbing Stairs	climbstairs.go
76	Minimum Window Substring	minwindow.go
79	Word Search	exist.go
94	Binary Tree Inorder Traversal	inordertraversal.go
100	Same Tree	issametree.go
110	Balanced Binary Tree	isbalanced.go
118	Pascal's Triangle	generate.go
119	Pascal's Triangle II	getrow.go
141	Linked List Cycle	hascycle.go
143	Reorder List	reorderlist.go
144	Binary Tree Preorder Traversal	preordertraversal.go
145	Binary Tree Postorder Traversal	postordertraversal.go
150	Evaluate Reverse Polish Notation	evalrpn.go
157	Read N Characters Given Read4	solution.go
159	Longest Substring with At Most Two Distinct Characters	lengthoflongestsubstringtwodistinct.go
160	Intersection of Two Linked Lists	getintersectionnode.go
163	Missing Ranges	findmissingranges.go
165	Compare Version Numbers	compareversion.go
168	Excel Sheet Column Title	converttotitle.go
169	Majority Element	majorityelement.go
171	Excel Sheet Column Number	titletonumber.go
175	Combine Two Tables	175.sql
181	Employees Earning More Than Their Managers	181.sql
182	Duplicate Emails	182.sql
183	Customers Who Never Order	183.sql
191	Number of 1 Bits	hammingweight.go
193	Valid Phone Numbers	193.sh
195	Tenth Line	195.sh
196	Delete Duplicate Emails	196.sql
197	Rising Temperature	197.sql
198	House Robber	rob.go
201	Bitwise AND of Numbers Range	rangebitwiseand.go
202	Happy Number	ishappy.go
205	Isomorphic Strings	isisomorphic.go
206	Reverse Linked List	reverselist.go
209	Minimum Size Subarray Sum	minsubarraylen.go
219	Contains Duplicate II	containsnearbyduplicate.go
222	Count Complete Tree Nodes	countnodes.go
226	Invert Binary Tree	inverttree.go
231	Power of Two	ispoweroftwo.go
232	Implement Queue using Stacks	myqueue.go
234	Palindrome Linked List	ispalindrome_2.go
237	Delete Node in a Linked List	deletenode.go
238	Product of Array Except Self	productexceptself.go
242	Valid Anagram	isanagram.go
243	Shortest Word Distance	shortestdistance.go
246	Strobogrammatic Number	isstrobogrammatic.go
252	Meeting Rooms	canattendmeetings.go
253	Meeting Rooms II	minmeetingrooms.go
256	Paint House	mincost_2.go
257	Binary Tree Paths	binarytreepaths.go
258	Add Digits	adddigits.go
266	Palindrome Permutation	canpermutepalindrome.go
268	Missing Number	missingnumber.go
276	Paint Fence	numways_2.go
279	Perfect Squares	numsquares.go
283	Move Zeroes	movezeroes.go
293	Flip Game	generatepossiblenextmoves.go
296	Best Meeting Point	mintotaldistance.go
300	Longest Increasing Subsequence	lengthoflis.go
303	Range Sum Query - Immutable	numarray.go
340	Longest Substring with At Most K Distinct Characters	lengthoflongestsubstringkdistinct.go
342	Power of Four	ispoweroffour.go
344	Reverse String	reversestring.go
346	Moving Average from Data Stream	movingaverage.go
349	Intersection of Two Arrays	intersection.go
359	Logger Rate Limiter	logger.go
367	Valid Perfect Square	isperfectsquare.go
368	Largest Divisible Subset	largestdivisiblesubset.go
380	Insert Delete GetRandom O(1)	randomizedset.go
387	First Unique Character in a String	firstuniqchar.go
404	Sum of Left Leaves	sumofleftleaves.go
405	Convert a Number to Hexadecimal	tohex.go
408	Valid Word Abbreviation	validwordabbreviation.go
451	Sort Characters By Frequency	frequencysort.go
452	Minimum Number of Arrows to Burst Balloons	findminarrowshots.go
455	Assign Cookies	findcontentchildren.go
458	Poor Pigs	poorpigs.go
485	Max Consecutive Ones	findmaxconsecutiveones_1.go
487	Max Consecutive Ones II	findmaxconsecutiveones_2.go
501	Find Mode in Binary Search Tree	findmode.go
506	Relative Ranks	findrelativeranks.go
509	Fibonacci Number	fib.go
513	Find Bottom Left Tree Value	findbottomleftvalue.go
525	Contiguous Array	findmaxlength.go
539	Minimum Time Difference	findmindifference.go
543	Diameter of Binary Tree	diameterofbinarytree.go
557	Reverse Words in a String III	reversewords.go
572	Subtree of Another Tree	issubtree.go
573	Squirrel Simulation	mindistance.go
576	Out of Boundary Paths	findpaths.go
606	Construct String from Binary Tree	tree2str.go
621	Task Scheduler	leastinterval.go
624	Maximum Distance in Arrays	maxdistance.go
643	Maximum Average Subarray I	findmaxaverage.go
645	Set Mismatch	finderrornums.go
647	Palindromic Substrings	countsubstrings.go
661	Image Smoother	imagesmoother.go
680	Valid Palindrome II	validpalindrome.go
704	Binary Search	search.go
713	Subarray Product Less Than K	numsubarrayproductlessthank.go
724	Find Pivot Index	pivotindex.go
739	Daily Temperatures	dailytemperatures.go
746	Min Cost Climbing Stairs	mincostclimbingstairs.go
779	K-th Symbol in Grammar	kthgrammar.go
791	Custom Sort String	customsortstring.go
844	Backspace String Compare	backspacecompare.go
867	Transpose Matrix	transpose.go
872	Leaf-Similar Trees	leafsimilar.go
876	Middle of the Linked List	middlenode.go
881	Boats to Save People	numrescueboats.go
905	Sort Array By Parity	sortarraybyparity.go
907	Sum of Subarray Minimums	sumsubarraymins.go
917	Reverse Only Letters	reverseonlyletters.go
930	Binary Subarrays With Sum	numsubarrayswithsum.go
931	Minimum Falling Path Sum	minfallingpathsum.go
935	Knight Dialer	knightdialer.go
938	Range Sum of BST	rangesumbst.go
948	Bag of Tokens	bagoftokensscore.go
977	Squares of a Sorted Array	sortedsquares.go
997	Find the Town Judge	findjudge.go
1002	Find Common Characters	commonchars.go
1004	Max Consecutive Ones III	longestones.go
1018	Binary Prefix Divisible By 5	prefixesdivby5.go
1026	Maximum Difference Between Node and Ancestor	maxancestordiff.go
1051	Height Checker	heightchecker.go
1057	Campus Bikes	assignbikes_1.go
1066	Campus Bikes II	assignbikes_2.go
1085	Sum of Digits in the Minimum Number	sumofdigits.go
1099	Two Sum Less Than K	twosumlessthank.go
1119	Remove Vowels from a String	removevowels.go
1120	Maximum Average Subtree	maximumaveragesubtree.go
1137	N-th Tribonacci Number	tribonacci.go
1143	Longest Common Subsequence	longestcommonsubsequence.go
1155	Number of Dice Rolls With Target Sum	numrollstotarget.go
1160	Find Words That Can Be Formed by Characters	countcharacters.go
1165	Single-Row Keyboard	calculatetime.go
1167	Minimum Cost to Connect Sticks	connectsticks.go
1171	Remove Zero Sum Consecutive Nodes from Linked List	removezerosumsublists.go
1207	Unique Number of Occurrences	uniqueoccurrences.go
1208	Get Equal Substrings Within Budget	equalsubstring.go
1216	Valid Palindrome III	isvalidpalindrome.go
1219	Path with Maximum Gold	getmaximumgold.go
1239	Maximum Length of a Concatenated String with Unique Characters	maxlength.go
1243	Array Transformation	transformarray.go
1266	Minimum Time Visiting All Points	mintimetovisitallpoints.go
1269	Number of Ways to Stay in the Same Place After Some Steps	numways_1.go
1272	Remove Interval	removeinterval.go
1287	Element Appearing More Than 25% In Sorted Array	findspecialinteger.go
1291	Sequential Digits	sequentialdigits.go
1295	Find Numbers with Even Number of Digits	findnumbers.go
1325	Delete Leaves With a Given Value	removeleafnodes.go
1337	The K Weakest Rows in a Matrix	kweakestrows.go
1347	Minimum Number of Steps to Make Two Strings Anagram	minsteps.go
1356	Sort Integers by The Number of 1 Bits	sortbybits.go
1360	Number of Days Between Two Dates	daysbetweendates.go
1361	Validate Binary Tree Nodes	validatebinarytreenodes.go
1413	Minimum Value to Get Positive Step by Step Sum	minstartvalue.go
1422	Maximum Score After Splitting a String	maxscore.go
1424	Diagonal Traverse II	finddiagonalorder.go
1428	Leftmost Column with at Least a One	leftmostcolumnwithone.go
1436	Destination City	destcity.go
1441	Build an Array With Stack Operations	buildarray.go
1456	Maximum Number of Vowels in a Substring of Given Length	maxvowels.go
1457	Pseudo-Palindromic Paths in a Binary Tree	pseudopalindromicpaths.go
1463	Cherry Pickup II	cherrypickup.go
1464	Maximum Product of Two Elements in an Array	maxproduct.go
1470	Shuffle the Array	shuffle.go
1480	Running Sum of 1d Array	runningsum.go
1481	Least Number of Unique Integers after K Removals	findleastnumofuniqueints.go
1496	Path Crossing	ispathcrossing.go
1503	Last Moment Before All Ants Fall Out of a Plank	getlastmoment.go
1535	Find the Winner of an Array Game	getwinner.go
1561	Maximum Number of Coins You Can Get	maxcoins.go
1578	Minimum Time to Make Rope Colorful	mincost_1.go
1581	Customer Who Visited but Did Not Make Any Transactions	1581.sql
1582	Special Positions in a Binary Matrix	numspecial.go
1603	Design Parking System	parkingsystem.go
1609	Even Odd Tree	isevenoddtree.go
1614	Maximum Nesting Depth of the Parentheses	maxdepth.go
1624	Largest Substring Between Two Equal Characters	maxlengthbetweenequalcharacters.go
1630	Arithmetic Subarrays	checkarithmeticsubarrays.go
1633	Percentage of Users Attended a Contest	1633.sql
1637	Widest Vertical Area Between Two Points Containing No Points	maxwidthofverticalarea.go
1642	Furthest Building You Can Reach	furthestbuilding.go
1652	Defuse the Bomb	decrypt.go
1657	Determine if Two Strings Are Close	closestrings.go
1662	Check If Two String Arrays are Equivalent	arraystringsareequal.go
1685	Sum of Absolute Differences in a Sorted Array	getsumabsolutedifferences.go
1688	Count of Matches in Tournament	numberofmatches.go
1669	Merge In Between Linked Lists	mergeinbetween.go
1700	Number of Students Unable to Eat Lunch	countstudents.go
1704	Determine if String Halves Are Alike	halvesarealike.go
1716	Calculate Money in Leetcode Bank	totalmoney.go
1720	Decode XORed Array	decode.go
1732	Find the Highest Altitude	largestaltitude.go
1743	Restore the Array From Adjacent Pairs	restorearray.go
1750	Minimum Length of String After Deleting Similar Ends	minimumlength.go
1757	Recyclable and Low Fat Products	1757.sql
1758	Minimum Changes To Make Alternating Binary String	minoperations_1.go
1759	Count Number of Homogenous Substrings	counthomogenous.go
1814	Count Nice Pairs in an Array	countnicepairs.go
1822	Sign of the Product of an Array	arraysign.go
1838	Frequency of the Most Frequent Element	maxfrequency.go
1845	Seat Reservation Manager	seatmanager.go
1846	Maximum Element After Decreasing and Rearranging	maximumelementafterdecrementingandrearranging.go
1877	Minimize Maximum Pair Sum in Array	minpairsum.go
1885	Count Pairs in Two Arrays	countpairs.go
1887	Reduction Operations to Make the Array Elements Equal	reductionoperations.go
1897	Redistribute Characters to Make All Strings Equal	makeequal.go
1903	Largest Odd Number in String	largestoddnumber.go
1913	Maximum Product Difference Between Two Pairs	maxproductdifference.go
1921	Eliminate Maximum Number of Monsters	eliminatemaximum.go
1930	Unique Length-3 Palindromic Subsequences	countpalindromicsubsequence.go
1961	Check If String Is a Prefix of Array	isprefixstring.go
1973	Count Nodes Equal to Sum of Descendants	equaltodescendants.go
1980	Find Unique Binary String	finddifferentbinarystring.go
1991	Find the Middle Index in Array	findmiddleindex.go
2000	Reverse Prefix of Word	reverseprefix.go
2032	Two Out of Three	twooutofthree.go
2090	K Radius Subarray Averages	getaverages.go
2108	Find First Palindromic String in the Array	firstpalindrome.go
2125	Number of Laser Beams in a Bank	numberofbeams.go
2149	Rearrange Array Elements by Sign	rearrangearray.go
2225	Find Players With Zero or One Losses	findwinners.go
2244	Minimum Rounds to Complete All Tasks	minimumrounds.go
2259	Remove Digit From Number to Maximize Result	removedigit.go
2264	Largest 3-Same-Digit Number in String	largestgoodinteger.go
2265	Count Nodes Equal to Average of Subtree	averageofsubtree.go
2331	Evaluate Boolean Binary Tree	evaluatetree.go
2353	Design a Food Rating System	foodratings.go
2357	Make Array Zero by Subtracting Equal Amounts	minimumoperations.go
2385	Amount of Time for Binary Tree to Be Infected	amountoftime.go
2391	Minimum Amount of Time to Collect Garbage	garbagecollection.go
2433	Find The Original Array of Prefix Xor	findarray.go
2441	Largest Positive Integer That Exists With Its Negative	findmaxk.go
2482	Difference Between Ones and Zeros in Row and Column	onesminuszeros.go
2485	Find the Pivot Integer	pivotinteger.go
2487	Remove Nodes From Linked List	removenodes.go
2490	Circular Sentence	iscircularsentence.go
2540	Minimum Common Value	getcommon.go
2549	Count Distinct Numbers on Board	distinctintegers.go
2595	Number of Even and Odd Bits	evenoddbit.go
2610	Convert an Array Into a 2D Array With Conditions	findmatrix.go
2620	Counter	createCounter.js
2667	Create Hello World Function	createHelloWorld.js
2704	To Be Or Not To Be	expect.js
2706	Buy Two Chocolates	buychoco.go
2785	Sort Vowels in a String	sortvowels.go
2816	Double a Number Represented as a Linked List	doubleit.go
2849	Determine if a Cell Is Reachable at a Given Time	isreachableattime.go
2864	Maximum Odd Binary Number	maximumoddbinarynumber.go
2870	Minimum Number of Operations to Make Array Empty	minoperations_2.go
2877	Create a DataFrame from List	create_dataframe.py
2958	Length of Longest Subarray With at Most K Frequency	maxsubarraylength.go
2966	Divide Array Into Arrays With Max Difference	dividearray.go
2971	Find Polygon With the Largest Perimeter	largestperimeter.go
3005	Count Elements With Maximum Frequency	maxfrequencyelements.go
3062	Winner of the Linked List Game	gameresult.go
3063	Linked List Frequency	frequenciesofelements.go
3075	Maximize Happiness of Selected Children	maximumhappinesssum.go

In revision

1. Longest Palindromic Substring
2. String to Integer (atoi)
3. Container With Most Water
4. Roman to Integer
5. Longest Common Prefix
6. Valid Parentheses
7. Merge Two Sorted Lists
8. Swap Nodes in Pairs
9. Remove Duplicates from Sorted Array
10. Remove Element
11. Find the Index of the First Occurrence in a String
12. Find First and Last Position of Element in Sorted Array
13. Valid Sudoku
14. Rotate Image
15. Spiral Matrix
16. Plus One
17. Add Binary
18. Simplify Path
19. Remove Duplicates from Sorted List II
20. Remove Duplicates from Sorted List
21. Merge Sorted Array
22. Reverse Linked List II
23. Validate Binary Search Tree
24. Symmetric Tree
25. Binary Tree Level Order Traversal
26. Binary Tree Zigzag Level Order Traversal
27. Maximum Depth of Binary Tree
28. Convert Sorted Array to Binary Search Tree
29. Minimum Depth of Binary Tree
30. Path Sum
31. Best Time to Buy and Sell Stock
32. Best Time to Buy and Sell Stock II
33. Valid Palindrome
34. Single Number
35. LRU Cache
36. Reverse Words in a String
37. Min Stack
38. Find Peak Element
39. Two Sum II - Input Array Is Sorted
40. Rotate Array
41. Reverse Bits
42. Binary Tree Right Side View
43. Remove Linked List Elements
44. Count Primes
45. Contains Duplicate
46. Implement Stack using Queues
47. Summary Ranges
48. Majority Element II
49. Lowest Common Ancestor of a Binary Tree
50. Sliding Window Maximum
51. Closest Binary Search Tree Value
52. First Bad Version
53. Find the Duplicate Number
54. Word Pattern
55. Power of Three
56. Odd Even Linked List
57. Increasing Triplet Subsequence
58. Counting Bits
59. Flatten Nested List Iterator
60. Integer Break
61. Reverse Vowels of a String
62. Intersection of Two Arrays II
63. Guess Number Higher or Lower
64. Ransom Note
65. Shuffle an Array
66. Find the Difference
67. Is Subsequence
68. Decode String
69. Fizz Buzz
70. Path Sum III
71. Find All Anagrams in a String
72. String Compression
73. Delete Node in a BST
74. Hamming Distance
75. Next Greater Element I
76. Diagonal Traverse
77. Find Largest Value in Each Tree Row
78. Minimum Absolute Difference in BST
79. Subarray Sum Equals K
80. Array Partition
81. Permutation in String
82. Can Place Flowers
83. Dota2 Senate
84. Search in a Binary Search Tree
85. Insert into a Binary Search Tree
86. Design HashMap
87. Design Linked List
88. Asteroid Collision
89. Find Smallest Letter Greater Than Target
90. Largest Number At Least Twice of Others
91. Jewels and Stones
92. Minimum Distance Between BST Nodes
93. Bus Routes
94. Binary Trees With Factors
95. Peak Index in a Mountain Array
96. Online Stock Span
97. Number of Recent Calls
98. Validate Stack Sequences
99. Longest Arithmetic Subsequence
100. Remove All Adjacent Duplicates In String
101. Greatest Common Divisor of Strings
102. Find in Mountain Array
103. Print in Order
104. Largest Unique Number
105. Snapshot Array
106. Maximum Level Sum of a Binary Tree
107. Maximum Number of Balloons
108. Count Vowels Permutation
109. Check If It Is a Straight Line
110. Count Number of Nice Subarrays
111. Convert Binary Number in a Linked List to Integer
112. Deepest Leaves Sum
113. Number of Steps to Reduce a Number to Zero
114. Count Negative Numbers in a Sorted Matrix
115. Longest ZigZag Path in a Binary Tree
116. Find Lucky Integer in an Array
117. Build Array Where You Can Find The Maximum Exactly K Comparisons
118. Constrained Subsequence Sum
119. Counting Elements
120. Kids With the Greatest Number of Candies
121. Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit
122. Count Good Nodes in Binary Tree
123. Max Dot Product of Two Subsequences
124. Longest Subarray of 1's After Deleting One Element
125. Can Make Arithmetic Progression From Sequence
126. Number of Good Pairs
127. Make The String Great
128. Richest Customer Wealth
129. Max Number of K-Sum Pairs
130. Maximum Erasure Value
131. Swapping Nodes in a Linked List
132. Sum of Unique Elements
133. Merge Strings Alternately
134. Maximum Score of a Good Subarray
135. Check if the Sentence Is Pangram
136. Check if All Characters Have Equal Number of Occurrences
137. Minimum Number of Operations to Make Array Continuous
138. Remove Colored Pieces if Both Neighbors are the Same Color
139. Parallel Courses III
140. Reverse Nodes in Even Length Groups
141. Delete the Middle Node of a Linked List
142. Maximum Twin Sum of a Linked List
143. Find the Difference of Two Arrays
144. Add Two Integers
145. Intersection of Multiple Arrays
146. Number of Flowers in Full Bloom
147. Minimum Consecutive Cards to Pick Up
148. Number of Ways to Split Array
149. Successful Pairs of Spells and Potions
150. Max Sum of a Pair With Equal Sum of Digits
151. First Letter to Appear Twice
152. Equal Row and Column Pairs
153. Removing Stars From a String
154. Using a Robot to Print the Lexicographically Smallest String
155. Total Cost to Hire K Workers
156. Design Graph With Shortest Path Calculator
157. Painting the Walls
158. Largest Submatrix With Rearrangements
159. Number of Ways to Divide a Long Corridor
160. Minimum One Bit Operations to Make Integers Zero
161. Decode Ways
162. String Compression II
163. Minimum Difficulty of a Job Schedule
164. Maximum Profit in Job Scheduling
165. Arithmetic Slices II - Subsequence
166. K Inverse Pairs Array
167. Number of Submatrices That Sum to Target
168. Partition Array for Maximum Sum
169. Meeting Rooms III
170. Tree Diameter
171. Cheapest Flights Within K Stops
172. Greatest Common Divisor Traversal
173. Find All People With Secret
174. Find All Duplicates in an Array
175. First Missing Positive