DSA Solutions & Explanations - FleetCode | Talentd

Title	Difficulty	Acceptance	Topics	Solution
1. Two Sum	Easy	54.3%	Array Hash Table	Read
2. Add Two Numbers	Medium	44.7%	Linked List Math+1	Read
3. Longest Substring Without Repeating Characters	Medium	35.8%	Hash Table Sliding Window+1	Read
4. Median of Two Sorted Arrays	Hard	42.1%	Array Binary Search+1	Read
5. Longest Palindromic Substring	Medium	34.8%	Dynamic Programming String+1	Read
6. Zigzag Conversion	Medium	49.9%	String	Read
7. Reverse Integer	Medium	29.5%	Math	Read
8. String to Integer (atoi)	Medium	18.3%	String	Read
9. Palindrome Number	Easy	58.0%	Math	Read
10. Regular Expression Matching	Hard	28.6%	Dynamic Programming Recursion+1	Read
11. Container With Most Water	Medium	56.6%	Array Greedy+1	Read
12. Integer to Roman	Medium	66.9%	Hash Table Math+1	Read
13. Roman to Integer	Easy	63.3%	Hash Table Math+1	Read
14. Longest Common Prefix	Easy	44.3%	String Trie	Read
15. 3Sum	Medium	35.8%	Array Sorting+1	Read
16. 3Sum Closest	Medium	46.3%	Array Sorting+1	Read
17. Letter Combinations of a Phone Number	Medium	62.3%	Backtracking Hash Table+1	Read
18. 4Sum	Medium	37.1%	Array Sorting+1	Read
19. Remove Nth Node From End of List	Medium	47.3%	Linked List Two Pointers	Read
20. Valid Parentheses	Easy	41.4%	Stack String	Read
21. Merge Two Sorted Lists	Easy	65.7%	Linked List Recursion	Read
22. Generate Parentheses	Medium	75.9%	Backtracking Dynamic Programming+1	Read
23. Merge k Sorted Lists	Hard	54.8%	Divide and Conquer Heap (Priority Queue)+2	Read
24. Swap Nodes in Pairs	Medium	65.8%	Linked List Recursion	Read
25. Reverse Nodes in k-Group	Hard	61.1%	Linked List Recursion	Read
26. Remove Duplicates from Sorted Array	Easy	58.4%	Array Two Pointers	Read
27. Remove Element	Easy	58.8%	Array Two Pointers	Read
28. Find the Index of the First Occurrence in a String	Easy	43.9%	String String Matching+1	Read
29. Divide Two Integers	Medium	17.9%	Bit Manipulation Math	Read
30. Substring with Concatenation of All Words	Hard	32.6%	Hash Table Sliding Window+1	Read
31. Next Permutation	Medium	41.6%	Array Two Pointers	Read
32. Longest Valid Parentheses	Hard	35.1%	Dynamic Programming Stack+1	Read
33. Search in Rotated Sorted Array	Medium	41.9%	Array Binary Search	Read
34. Find First and Last Position of Element in Sorted Array	Medium	45.6%	Array Binary Search	Read
35. Search Insert Position	Easy	47.7%	Array Binary Search	Read
36. Valid Sudoku	Medium	61.0%	Array Hash Table+1	Read
37. Sudoku Solver	Hard	63.5%	Array Backtracking+2	Read
38. Count and Say	Medium	57.1%	String	Read
39. Combination Sum	Medium	73.2%	Array Backtracking	Read
40. Combination Sum II	Medium	56.8%	Array Backtracking	Read
41. First Missing Positive	Hard	40.2%	Array Hash Table	Read
42. Trapping Rain Water	Hard	63.6%	Array Dynamic Programming+3	Read
43. Multiply Strings	Medium	41.3%	Math Simulation+1	Read
44. Wildcard Matching	Hard	28.9%	Dynamic Programming Greedy+2	Read
45. Jump Game II	Medium	40.9%	Array Dynamic Programming+1	Read
46. Permutations	Medium	79.6%	Array Backtracking	Read
47. Permutations II	Medium	60.5%	Array Backtracking	Read
48. Rotate Image	Medium	76.4%	Array Math+1	Read
49. Group Anagrams	Medium	69.8%	Array Hash Table+2	Read
50. Pow(x, n)	Medium	36.0%	Math Recursion	Read

#1Easy

Two Sum

ArrayHash Table

Acceptance: 54.3%

#2Medium

Add Two Numbers

Linked ListMathRecursion

Acceptance: 44.7%

#3Medium

Longest Substring Without Repeating Characters

Hash TableSliding WindowString

Acceptance: 35.8%

#4Hard

Median of Two Sorted Arrays

ArrayBinary SearchDivide and Conquer

Acceptance: 42.1%

#5Medium

Longest Palindromic Substring

Dynamic ProgrammingStringTwo Pointers

Acceptance: 34.8%

#6Medium

Zigzag Conversion

String

Acceptance: 49.9%

#7Medium

Reverse Integer

Math

Acceptance: 29.5%

#8Medium

String to Integer (atoi)

String

Acceptance: 18.3%

#9Easy

Palindrome Number

Math

Acceptance: 58.0%

#10Hard

Regular Expression Matching

Dynamic ProgrammingRecursionString

Acceptance: 28.6%

#11Medium

Container With Most Water

ArrayGreedyTwo Pointers

Acceptance: 56.6%

#12Medium

Integer to Roman

Hash TableMathString

Acceptance: 66.9%

#13Easy

Roman to Integer

Hash TableMathString

Acceptance: 63.3%

#14Easy

Longest Common Prefix

StringTrie

Acceptance: 44.3%

#15Medium

3Sum

ArraySortingTwo Pointers

Acceptance: 35.8%

#16Medium

3Sum Closest

ArraySortingTwo Pointers

Acceptance: 46.3%

#17Medium

Letter Combinations of a Phone Number

BacktrackingHash TableString

Acceptance: 62.3%

#18Medium

4Sum

ArraySortingTwo Pointers

Acceptance: 37.1%

#19Medium

Remove Nth Node From End of List

Linked ListTwo Pointers

Acceptance: 47.3%

#20Easy

Valid Parentheses

StackString

Acceptance: 41.4%

#21Easy

Merge Two Sorted Lists

Linked ListRecursion

Acceptance: 65.7%

#22Medium

Generate Parentheses

BacktrackingDynamic ProgrammingString

Acceptance: 75.9%

#23Hard

Merge k Sorted Lists

Divide and ConquerHeap (Priority Queue)Linked List+1

Acceptance: 54.8%

#24Medium

Swap Nodes in Pairs

Linked ListRecursion

Acceptance: 65.8%

#25Hard

Reverse Nodes in k-Group

Linked ListRecursion

Acceptance: 61.1%

#26Easy

Remove Duplicates from Sorted Array

ArrayTwo Pointers

Acceptance: 58.4%

#27Easy

Remove Element

ArrayTwo Pointers

Acceptance: 58.8%

#28Easy

Find the Index of the First Occurrence in a String

StringString MatchingTwo Pointers

Acceptance: 43.9%

#29Medium

Divide Two Integers

Bit ManipulationMath

Acceptance: 17.9%

#30Hard

Substring with Concatenation of All Words

Hash TableSliding WindowString

Acceptance: 32.6%

#31Medium

Next Permutation

ArrayTwo Pointers

Acceptance: 41.6%

#32Hard

Longest Valid Parentheses

Dynamic ProgrammingStackString

Acceptance: 35.1%

#33Medium

Search in Rotated Sorted Array

ArrayBinary Search

Acceptance: 41.9%

#34Medium

Find First and Last Position of Element in Sorted Array

ArrayBinary Search

Acceptance: 45.6%

#35Easy

Search Insert Position

ArrayBinary Search

Acceptance: 47.7%

#36Medium

Valid Sudoku

ArrayHash TableMatrix

Acceptance: 61.0%

#37Hard

Sudoku Solver

ArrayBacktrackingHash Table+1

Acceptance: 63.5%

#38Medium

Count and Say

String

Acceptance: 57.1%

#39Medium

Combination Sum

ArrayBacktracking

Acceptance: 73.2%

#40Medium

Combination Sum II

ArrayBacktracking

Acceptance: 56.8%

#41Hard

First Missing Positive

ArrayHash Table

Acceptance: 40.2%

#42Hard

Trapping Rain Water

ArrayDynamic ProgrammingMonotonic Stack+2

Acceptance: 63.6%

#43Medium

Multiply Strings

MathSimulationString

Acceptance: 41.3%

#44Hard

Wildcard Matching

Dynamic ProgrammingGreedyRecursion+1

Acceptance: 28.9%

#45Medium

Jump Game II

ArrayDynamic ProgrammingGreedy

Acceptance: 40.9%

#46Medium

Permutations

ArrayBacktracking

Acceptance: 79.6%

#47Medium

Permutations II

ArrayBacktracking

Acceptance: 60.5%

#48Medium

Rotate Image

ArrayMathMatrix

Acceptance: 76.4%

#49Medium

Group Anagrams

ArrayHash TableSorting+1

Acceptance: 69.8%

#50Medium

Pow(x, n)

MathRecursion

Acceptance: 36.0%

Solutions & Explanations

Two Sum

Add Two Numbers

Longest Substring Without Repeating Characters

Median of Two Sorted Arrays

Longest Palindromic Substring

Zigzag Conversion

Reverse Integer

String to Integer (atoi)

Palindrome Number

Regular Expression Matching

Container With Most Water

Integer to Roman

Roman to Integer

Longest Common Prefix

3Sum

3Sum Closest

Letter Combinations of a Phone Number

4Sum

Remove Nth Node From End of List

Valid Parentheses

Merge Two Sorted Lists

Generate Parentheses

Merge k Sorted Lists

Swap Nodes in Pairs

Reverse Nodes in k-Group

Remove Duplicates from Sorted Array

Remove Element

Find the Index of the First Occurrence in a String

Divide Two Integers

Substring with Concatenation of All Words

Next Permutation

Longest Valid Parentheses

Search in Rotated Sorted Array

Find First and Last Position of Element in Sorted Array

Search Insert Position

Valid Sudoku

Sudoku Solver

Count and Say

Combination Sum

Combination Sum II

First Missing Positive

Trapping Rain Water

Multiply Strings

Wildcard Matching

Jump Game II

Permutations

Permutations II

Rotate Image

Group Anagrams

Pow(x, n)

Master DSA with Step-by-Step Solutions

How to Use These Solutions

Solutions & Explanations

Two Sum

Add Two Numbers

Longest Substring Without Repeating Characters

Median of Two Sorted Arrays

Longest Palindromic Substring

Zigzag Conversion

Reverse Integer

String to Integer (atoi)

Palindrome Number

Regular Expression Matching

Container With Most Water

Integer to Roman

Roman to Integer

Longest Common Prefix

3Sum

3Sum Closest

Letter Combinations of a Phone Number

4Sum

Remove Nth Node From End of List

Valid Parentheses

Merge Two Sorted Lists

Generate Parentheses

Merge k Sorted Lists

Swap Nodes in Pairs

Reverse Nodes in k-Group

Remove Duplicates from Sorted Array