Go LeetCode Solutions

Repository with my solutions to various LeetCode problems.

To solve these problems I use functions from Golang Standard Library where applicable...

• unicode, strings, sort, slices, time, strconv...

My main focus is these tags: Array, Hash Table, String.

Tips & Tricks

Read this document for all tips and tricks that are useful for solving these problems.

Solutions

#	Title	Tags	Difficulty
1	Two Sum	Array, Hash Table	🟢 Easy
3	Longest Substring Without Repeating Characters	Hash Table, Sliding Window, String	🟡 Medium
9	Palindrome Number	Math	🟢 Easy
13	Roman to Integer	Hash Table, Math, String	🟢 Easy
14	Longest Common Prefix	String, Trie	🟢 Easy
20	Valid Parentheses	Stack, String	🟢 Easy
21	Merge Two Sorted Lists	Linked List, Recursion	🟢 Easy
26	Remove Duplicates from Sorted Array	Array, Two Pointers	🟢 Easy
27	Remove Element	Array, Two Pointers	🟢 Easy
28	Find the Index of the First Occurrence in a String	String, String Matching, Two Pointers	🟢 Easy
35	Search Insert Position	Array, Binary Search	🟢 Easy
58	Length of Last Word	String	🟢 Easy
66	Plus One	Array, Math	🟢 Easy
67	Add Binary	Bit Manipulation, Math, Simulation, String	🟢 Easy
69	Sqrt(x)	Bit Search, Math	🟢 Easy
70	Climbing Stairs	Dynamic Programming, Math, Memoization	🟢 Easy
83	Remove Duplicates from Sorted List	Linked List	🟢 Easy
88	Merge Sorted Array	Array, Sorting, Two Pointers	🟢 Easy
94	Binary Tree Inorder Traversal	Binary Tree, DFS, Stack, Tree	🟢 Easy
100	Same Tree	Binary Tree, BFS, DFS, Stack, Tree	🟢 Easy
101	Symmetric Tree	Binary Tree, BFS, DFS, Stack, Tree	🟢 Easy
104	Maximum Depth of Binary Tree	Binary Tree, BFS, DFS, Stack, Tree	🟢 Easy
118	Pascal's Triangle	Array, Dynamic Programming	🟢 Easy
119	Pascal's Triangle II	Array, Dynamic Programming	🟢 Easy
121	Best Time to Buy and Sell Stock	Array, Dynamic Programming	🟢 Easy
125	Valid Palindrome	String, Two Pointers	🟢 Easy
136	Single Number	Array, Bit Manipulation	🟢 Easy
151	Reverse Words in a String	String, Two Pointers	🟡 Medium
167	Two Sum II	Array, Binary Search, Two Pointers	🟡 Medium
168	Excel Sheet Column Title	Math, String	🟢 Easy
169	Majority Element	Array, Counting, Hash Table, Sorting	🟢 Easy
171	Excel Sheet Column Number	Math, String	🟢 Easy
190	Reverse Bits	Bit Manipulation, Divide and Conquer	🟢 Easy
191	Number of 1 Bits	Bit Manipulation, Divide and Conquer	🟢 Easy
198	House Robber	Array, Dynamic Programming	🟡 Medium
205	Isomorphic Strings	Hash Table, String	🟢 Easy
206	Reverse Linked List	Linked List, Recursion	🟢 Easy
217	Contains Duplicate	Array, Hash Table, Sorting	🟢 Easy
219	Contains Duplicate II	Array, Hash Table, Sliding Window	🟢 Easy
228	Summary Ranges	Array	🟢 Easy
242	Valid Anagram	Hash Table, Sorting, String	🟢 Easy
257	Binary Tree Paths	Backtracking, Binary Tree, DFS, Tree, String	🟢 Easy
258	Add Digits	Number Theory, Math, Simulation	🟢 Easy
268	Missing Number	Array, Bit Manipulation, Hash Table, Sorting	🟢 Easy
283	Move Zeroes	Array, Two Pointers	🟢 Easy
290	Word Pattern	Hash Table, String	🟢 Easy
338	Counting Bits	Bit Manipulation, Dynamic Programming	🟢 Easy
344	Reverse String	String, Two Pointers	🟢 Easy
345	Reverse Vowels of a String	String, Two Pointers	🟢 Easy
349	Intersection of Two Arrays	Array, Harsh Table, Sorting	🟢 Easy
350	Intersection of Two Arrays II	Array, Harsh Table, Sorting	🟢 Easy
383	Ransom Note	Counting, Hash Table, String	🟢 Easy
387	First Unique Character in a String	Counting, Hash Table, String, Queue	🟢 Easy
389	Find the Difference	Bit Manipulation, Hash Table, Sorting, String	🟢 Easy
392	Is Subsequence	Dynamic Programming, String, Two Pointers	🟢 Easy
401	Binary Watch	Backtracking, Bit Manipulation	🟢 Easy
405	Convert a Number to Hexadecimal	Bit Manipulation, Math	🟢 Easy
412	Fizz Buzz	Math, Simulation, String	🟢 Easy
415	Add Strings	Math, Simulation, String	🟢 Easy
434	Number of Segments in a String	String	🟢 Easy
448	Find All Numbers Disappeared in an Array	Array, Hash Table	🟢 Easy
455	Assign Cookies	Array, Greedy, Sorting, Two Pointers	🟢 Easy
459	Repeated Substring Pattern	String, String Matching	🟢 Easy
463	Island Perimeter	Array, DFS, BFS, Matrix	🟢 Easy
476	Number Complement	Bit Manipulation	🟢 Easy
482	License Key Formatting	String	🟢 Easy
485	Max Consecutive Ones	Array	🟢 Easy
500	Keyboard Row	Array, Hash Table, String	🟢 Easy
509	Fibonacci Number	Dynamic Programming, Math, Memoization, Recursion	🟢 Easy
520	Detect Capital	String	🟢 Easy
551	Student Attendance Record I	String	🟢 Easy
557	Reverse Words in a String III	String, Two Pointers	🟢 Easy
599	Minimum Index Sum of Two Lists	Array, Hash Table, String	🟢 Easy
657	Robot Return to Origin	Simulation, String	🟢 Easy
682	Baseball Game	Array, Stack, Simulation	🟢 Easy
693	Binary Number with Alternating Bits	Bit Manipulation	🟢 Easy
709	To Lower Case	String	🟢 Easy
746	Min Cost Climbing Stairs	Array, Dynamic Programming	🟢 Easy
762	Prime Number of Set Bits in Binary Representation	Math, Bit Manipulation	🟢 Easy
771	Jewels and Stones	Hash Table, String	🟢 Easy
796	Rotate String	String Matching, String	🟢 Easy
804	Unique Morse Code Words	Array, Hash Table, String	🟢 Easy
806	Number of Lines To Write String	Array, String	🟢 Easy
819	Most Common Word	Counting, Hash Table, String	🟢 Easy
821	Shortest Distance to a Character	Array, String, Two Pointers	🟢 Easy
824	Goat Latin	String	🟢 Easy
830	Positions of Large Groups	String	🟢 Easy
832	Flipping an Image	Array, Simulation, Matrix	🟢 Easy
844	Backspace String Compare	Simulation, Stack, String, Two Pointers	🟢 Easy
868	Binary Gap	Bit Manipulation	🟢 Easy
884	Uncommon Words from Two Sentences	Hash Table, String	🟢 Easy
944	Delete Columns to Make Sorted	Array, String	🟢 Easy
961	N-Repeated Element in Size 2N Array	Array, Hash Table	🟢 Easy
1002	Find Common Characters	Array, Hash Table, String	🟢 Easy
1047	Remove All Adjacent Duplicates In String	Stack, String	🟢 Easy
1051	Height Checker	Array, Counting Sort, Sorting	🟢 Easy
1078	Occurrences After Bigram	String	🟢 Easy
1089	Duplicate Zeros	Array, Two Pointers	🟢 Easy
1108	Defanging an IP Address	String	🟢 Easy
1154	Day of the Year	Math, String	🟢 Easy
1189	Maximum Number of Balloons	Counting, Hash Table, String	🟢 Easy
1207	Unique Number of Occurrences	Array, Hash Table	🟢 Easy
1221	Split a String in Balanced Strings	Counting, Greedy, String	🟢 Easy
1275	Find Winner on a Tic Tac Toe Game	Array, Hash Table, Matrix, Simulation	🟢 Easy
1287	Element Appearing More Than 25% In Sorted Array	Array	🟢 Easy
1304	Find N Unique Integers Sum up to Zero	Array, Math	🟢 Easy
1309	Decrypt String from Alphabet to Integer Mapping	String	🟢 Easy
1313	Decompress Run-Length Encoded List	Array	🟢 Easy
1331	Rank Transform of an Array	Array, Hash Table, Sorting	🟢 Easy
1346	Check If N and Its Double Exist	Array, Binary Search, Hash Table	🟢 Easy
1351	Count Negative Numbers in a Sorted Matrix	Array, Binary Search, Matrix	🟢 Easy
1360	Number of Days Between Two Dates	Math, String	🟢 Easy
1365	How Many Numbers Are Smaller Than the Current Number	Array, Counting, Hash Table, Sorting	🟢 Easy
1389	Create Target Array in the Given Order	Array, Simulation	🟢 Easy
1408	String Matching in an Array	Array, String, String Matching	🟢 Easy
1431	Kids With the Greatest Number of Candies	Array	🟢 Easy
1436	Destination City	Hash Table, String	🟢 Easy
1455	Check If a Word Occurs As a Prefix	String Manipulation, String	🟢 Easy
1470	Shuffle the Array	Array	🟢 Easy
1480	Running Sum of 1d Array	Array, Prefix Sum	🟢 Easy
1486	XOR Operation in an Array	Bit Manipulation, Math	🟢 Easy
1496	Path Crossing	Hash Table, String	🟢 Easy
1507	Reformat Date	String	🟢 Easy
1512	Number of Good Pairs	Array, Counting, Hash Table, Math	🟢 Easy
1518	Water Bottles	Math, Simulation	🟢 Easy
1528	Shuffle String	Array, String	🟢 Easy
1550	Three Consecutive Odds	Array	🟢 Easy
1556	Thousand Separator	String	🟢 Easy
1588	Sum of All Odd Length Subarrays	Array, Math, Prefix Sum	🟢 Easy
1592	Rearrange Spaces Between Words	String	🟢 Easy
1614	Maximum Nesting Depth of the Parentheses	Stack, String	🟢 Easy
1624	Largest Substring Between Two Equal Characters	Hash Table, String	🟢 Easy
1662	Check If Two String Arrays are Equivalent	Array, String	🟢 Easy
1670	Richest Customer Wealth	Array, Matrix	🟢 Easy
1678	Goal Parser Interpretation	String	🟢 Easy
1684	Count the Number of Consistent Strings	Array, Bit Manipulation, Hash Table, String	🟢 Easy
1704	Determine if String Halves Are Alike	Counting, String	🟢 Easy
1720	Decode XORed Array	Array, Bit Manipulation	🟢 Easy
1742	Maximum Number of Balls in a Box	Counting, Hash Table, Math	🟢 Easy
1768	Merge Strings Alternately	String, Two Pointers	🟢 Easy
1773	Count Items Matching a Rule	Array, String	🟢 Easy
1796	Second Largest Digit in a String	Hash Table, String	🟢 Easy
1805	Number of Different Integers in a String	Hash Table, String	🟢 Easy
1812	Determine Color of a Chessboard Square	Math, String	🟢 Easy
1816	Truncate Sentence	Array, String	🟢 Easy
1832	Check if the Sentence Is Pangram	Hash Table, String	🟢 Easy
1844	Replace All Digits with Characters	String	🟢 Easy
1859	Sorting the Sentence	Sorting, String	🟢 Easy
1863	Sum of All Subset XOR Totals	Array, Bit Manipulation	🟢 Easy
1876	Substrings of Size Three with Distinct Characters	Counting, Hash Table, Sliding Window, String	🟢 Easy
1880	Check if Word Equals Summation of Two Words	String	🟢 Easy
1913	Maximum Product Difference Between Two Pairs	Array, Sorting	🟢 Easy
1920	Build Array from Permutation	Array, Simulation	🟢 Easy
1929	Concatenation of Array	Array	🟢 Easy
1941	Check if All Characters Have Equal Number of Occurrences	Counting, Hash Table, String	🟢 Easy
1967	Number of Strings That Appear as Substrings in Word	String	🟢 Easy
2000	Reverse Prefix of Word	String, Two Pointers	🟢 Easy
2006	Count Number of Pairs With Absolute Difference K	Array, Hash Table, Counting,	🟢 Easy
2011	Final Value of Variable After Performing Operations	Array, Simulation, String	🟢 Easy
2085	Count Common Words With One Occurrence	Array, Counting, Hash Table, String	🟢 Easy
2103	Rings and Rods	Hash Table, String	🟢 Easy
2114	Maximum Number of Words Found in Sentences	Array, String	🟢 Easy
2119	A Number After a Double Reversal	Math	🟢 Easy
2129	Capitalize the Title	String	🟢 Easy
2160	Minimum Sum of Four Digit Number After Splitting Digits	Greedy, Math, Sorting	🟢 Easy
2169	Count Operations to Obtain Zero	Math, Simulation	🟢 Easy
2185	Counting Words With a Given Prefix	Array, String	🟢 Easy
2194	Cells in a Range on an Excel Sheet	String	🟢 Easy
2215	Find the Difference of Two Arrays	Array, Hash Table	🟢 Easy
2283	Check if Number Has Equal Digit Count and Digit Value	Counting, Hash Table, String	🟢 Easy
2309	Greatest English Letter in Upper and Lower Case	Enumeration, Hash Table, String	🟢 Easy
2315	Count Asterisks	String	🟢 Easy
2325	Decode the Message	Hash Table, String	🟢 Easy
2418	Sort the People	Array, Hash Table, Sorting, String	🟢 Easy
2446	Determine if Two Events Have Conflict	Array, String	🟢 Easy
2451	Odd String Difference	Array, Hash Table, String	🟢 Easy
2496	Maximum Value of a String in an Array	Array, String	🟢 Easy
2506	Count Pairs of Similar Strings	Array, Hash Table, String	🟢 Easy
2540	Minimum Common Value	Array, Binary Search, Hash Table, Two Pointers	🟢 Easy
2553	Separate the Digits in an Array	Array, Simulation	🟢 Easy
2574	Left and Right Sum Differences	Array, Prefix Sum	🟢 Easy
2586	Count the Number of Vowel Strings in Range	Array, String	🟢 Easy
2595	Number of Even and Odd Bits	Bit Manipulation	🟢 Easy
2656	Maximum Sum With Exactly K Elements	Array, Greedy	🟢 Easy
2696	Minimum String Length After Removing Substrings	Simulation, Stack, String	🟢 Easy
2716	Minimize String Length	Hash Table, String	🟢 Easy
2744	Find Maximum Number of String Pairs	Array, Hash Table, Simulation, String	🟢 Easy
2778	Sum of Squares of Special Elements	Array, Simulation	🟢 Easy
2788	Split Strings by Separator	Array, String	🟢 Easy
2798	Number of Employees Who Met the Target	Array, Enumeration	🟢 Easy
2810	Faulty Keyboard	Simulation, String	🟢 Easy
2824	Count Pairs Whose Sum is Less than Target	Array, Sorting, Two Pointers	🟢 Easy
2828	Check if a String Is an Acronym of Words	Array, String	🟢 Easy
2843	Count Symmetric Integers	Enumeration, Math	🟢 Easy
2848	Points That Intersect With Cars	Hash Table, Math, Prefix Sum	🟢 Easy
2859	Sum of Values at Indices With K Set Bits	Array, Bit Manipulation	🟢 Easy
2864	Maximum Odd Binary Number	Greedy, Math, String	🟢 Easy
2894	Divisible and Non-divisible Sums Difference	Math	🟢 Easy
2917	Find the K-or of an Array	Array, Bit Manipulation	🟢 Easy
2932	Maximum Strong Pair XOR I	Array, Bit Manipulation, Hash Table	🟢 Easy
2942	Find Words Containing Character	Array, String	🟢 Easy
2960	Count Tested Devices After Test Operations	Array, Counting, Simulation	🟢 Easy
2974	Minimum Number Game	Array, Simulation, Sorting	🟢 Easy
3005	Count Elements With Maximum Frequency	Array, Counting, Hash Table	🟢 Easy
3019	Number of Changing Keys	String	🟢 Easy
3028	Ant on the Boundary	Array, Simulation, Prefix Sum	🟢 Easy
3046	Split the Array	Array, Hash Table, Counting	🟢 Easy
3074	Apple Redistribution into Boxes	Array, Greedy, Sorting	🟢 Easy
3095	Shortest Subarray With OR at Least K I	Array, Bit Manipulation, Sliding Window	🟢 Easy
3099	Harshad Number	Math	🟢 Easy
3110	Score of String	String	🟢 Easy
3120	Count the Number of Special Characters I	Hash Table, String	🟢 Easy
3136	Valid Word	String	🟢 Easy
3151	Special Array I	Array	🟢 Easy
3158	Find the XOR of Numbers Which Appear Twice	Array, Bit Manipulation, Hash Table	🟢 Easy
3162	Find the Number of Good Pairs I	Array, Hash Table	🟢 Easy
3168	Minimum Number of Chairs in a Waiting Room	Simulation, String	🟢 Easy
3174	Clear Digits	Hash Table, Simulation, String	🟢 Easy
3194	Minimum Average of Smallest and Largest Elements	Array, Sorting	🟢 Easy
3206	Alternating Groups I	Array, Sliding Window	🟢 Easy
3210	Find the Encrypted String	String	🟢 Easy
3216	Lexicographically Smallest String After a Swap	Greedy, String	🟢 Easy
3226	Number of Bit Changes to Make Two Integers Equal	Bit Manipulation	🟢 Easy
3232	Find if Digit Game Can Be Won	Array, Math	🟢 Easy
3242	Design Neighbor Sum Service	Array, Hash Table, Matrix, Simulation	🟢 Easy
3248	Snake in Matrix	Array, Simulation, String	🟢 Easy
3258	Count Substrings That Satisfy K-Constraint I	Sliding Window, String	🟢 Easy
3264	Final Array State After K Multiplication Operations I	Array, Math, Simulation	🟢 Easy
3289	The Two Sneaky Numbers of Digitville	Array, Hash Table, Math	🟢 Easy
3280	Convert Date to Binary	Math, String	🟢 Easy
3285	Find Indices of Stable Mountains	Array	🟢 Easy
3270	Find the Key of the Numbers	Math	🟢 Easy
3274	Check if Two Chessboard Squares Have the Same Color	Math, String	🟢 Easy
3300	Minimum Element After Replacement With Digit Sum	Array, Math	🟢 Easy
3304	Find the K-th Character in String Game I	Bit Manipulation, Math, Simulation	🟢 Easy

Legend:

• BFS - Breadth-First Search
• DFS - Depth-First Search

Todo

Solve problems related to other tags and difficulties... 🤔

Static Analysis

Run golangci-lint command. There is a hidden configuration file for this tool inside root directory .golangci.yml.

$ golangci-lint --color always run --verbose ./...

Testing

$ go test -v ./...

Benchmarking

Many solutions contain benchmarks.

$ go test -bench=. -benchmem ./1---Two-Sum
goos: linux
goarch: amd64
cpu: 13th Gen Intel(solutions/R) Core(solutions/TM) i7-13700K
Benchmark_twoSum_Iterations-24    	100000000	        13.83 ns/op	      16 B/op	       1 allocs/op
Benchmark_twoSum_Map-24           	43644519	        25.72 ns/op	      16 B/op	       1 allocs/op
PASS

Credits

The gopher image at the top is taken from: https://github.com/MariaLetta/free-gophers-pack