LeetCode-in-C

C-based LeetCode algorithm problem solutions, regularly updated.

"For coding interview preparation, LeetCode is one of the best online resource providing a rich library of more than 300 real coding interview questions for you to practice from using one of the 7 supported languages - C, C++, Java, Python, C#, JavaScript, Ruby."

• Data Structure I
• Data Structure II
• Algorithm I
• Algorithm II
• Binary Search I
• Binary Search II
• Dynamic Programming I
• Programming Skills I
• Programming Skills II
• Graph Theory I
• SQL I
• Level 1
• Level 2
• Udemy

Data Structure I

Day 1 Array

Day 2 Array

0001	Two Sum	Data_Structure_I_Day_2_Array	Big_O_Time_O(n)_Space_O(n), AI_can_be_used_to_solve_the_task	2	99.56

Day 3 Array

Day 4 Array

Day 5 Array

Day 6 String

Day 7 Linked List

Day 8 Linked List

Day 9 Stack Queue

Day 10 Tree

Day 11 Tree

Day 12 Tree

Day 13 Tree

Day 14 Tree

Data Structure II

Day 1 Array

Day 2 Array

Day 3 Array

Day 4 Array

Day 5 Array

Day 6 String

Day 7 String

Day 8 String

Day 9 String

0005	Longest Palindromic Substring	Medium	Top_100_Liked_Questions, Top_Interview_Questions, String, Dynamic_Programming, Big_O_Time_O(n)_Space_O(n)	2	97.74

Day 10 Linked List

0002	Add Two Numbers	Medium	Top_100_Liked_Questions, Top_Interview_Questions, Math, Linked_List, Recursion, Big_O_Time_O(max(N,M))_Space_O(max(N,M)), AI_can_be_used_to_solve_the_task	12	70.50

Day 11 Linked List

Day 12 Linked List

Day 13 Linked List

Day 14 Stack Queue

Day 15 Tree

Day 16 Tree

Day 17 Tree

Day 18 Tree

Day 19 Graph

Day 20 Heap Priority Queue

Day 21 Heap Priority Queue

Algorithm I

Day 1 Binary Search

Day 2 Two Pointers

Day 3 Two Pointers

Day 4 Two Pointers

Day 5 Two Pointers

Day 6 Sliding Window

0003	Longest Substring Without Repeating Characters	Medium	Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Sliding_Window, Big_O_Time_O(n)_Space_O(1)	15	29.93

Day 7 Breadth First Search Depth First Search

Day 8 Breadth First Search Depth First Search

Day 9 Breadth First Search Depth First Search

Day 10 Recursion Backtracking

Day 11 Recursion Backtracking

Day 12 Dynamic Programming

Day 13 Bit Manipulation

Day 14 Bit Manipulation

Algorithm II

Day 1 Binary Search

Day 2 Binary Search

Day 3 Two Pointers

Day 4 Two Pointers

Day 5 Sliding Window

Day 6 Breadth First Search Depth First Search

Day 7 Breadth First Search Depth First Search

Day 8 Breadth First Search Depth First Search

Day 9 Recursion Backtracking

Day 10 Recursion Backtracking

Day 11 Recursion Backtracking

Day 12 Dynamic Programming

Day 13 Dynamic Programming

Day 14 Dynamic Programming

0005	Longest Palindromic Substring	Medium	Top_100_Liked_Questions, Top_Interview_Questions, String, Dynamic_Programming, Big_O_Time_O(n)_Space_O(n)	2	97.74

Day 15 Dynamic Programming

Day 16 Dynamic Programming

Day 17 Dynamic Programming

Day 18 Dynamic Programming

Day 19 Bit Manipulation

Day 20 Others

Day 21 Others

Binary Search I

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

Day 7

Day 8

Day 9

Day 10

Day 11

Day 12

Binary Search II

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

Day 7

Day 8

Day 9

Day 10

Day 11

Day 12

Day 13

Day 14

Day 15

Day 16

Day 17

Day 18

Day 19

Day 20

Dynamic Programming I

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

Day 7

Day 8

Day 9

Day 10

Day 11

Day 12

Day 13

Day 14

Day 15

Day 16

Day 17

0005	Longest Palindromic Substring	Medium	Top_100_Liked_Questions, Top_Interview_Questions, String, Dynamic_Programming, Big_O_Time_O(n)_Space_O(n)	2	97.74

Day 18

Day 19

Day 20

Day 21

Programming Skills I

Day 1 Basic Data Type

Day 2 Operator

Day 3 Conditional Statements

Day 4 Loop

Day 5 Function

Day 6 Array

Day 7 Array

Day 8 String

Day 9 String

Day 10 Linked List and Tree

Day 11 Containers and Libraries

Day 12 Class and Object

Programming Skills II

Day 1

Day 2

Day 3

Day 4

Day 5

Day 6

Day 7

Day 8

Day 9

Day 10

Day 11

Day 12

Day 13

Day 14

Day 15

0002	Add Two Numbers	Medium	Top_100_Liked_Questions, Top_Interview_Questions, Math, Linked_List, Recursion, Big_O_Time_O(max(N,M))_Space_O(max(N,M)), AI_can_be_used_to_solve_the_task	12	70.50

Day 16

Day 17

Day 18

Day 19

Day 20

Graph Theory I

Day 1 Matrix Related Problems

Day 2 Matrix Related Problems

Day 3 Matrix Related Problems

Day 4 Matrix Related Problems

Day 5 Matrix Related Problems

Day 6 Matrix Related Problems

Day 7 Standard Traversal

Day 8 Standard Traversal

Day 9 Standard Traversal

Day 10 Standard Traversal

Day 11 Breadth First Search

Day 12 Breadth First Search

Day 13 Graph Theory

Day 14 Graph Theory

SQL I

Day 1 Select

Day 2 Select and Order

Day 3 String Processing Functions

Day 4 Union and Select

Day 5 Union

Day 6 Union

Day 7 Function

Day 8 Function

Day 9 Control of Flow

Day 10 Where

Level 1

Day 1 Prefix Sum

Day 2 String

Day 3 Linked List

Day 4 Linked List

Day 5 Greedy

Day 6 Tree

Day 7 Binary Search

Day 8 Binary Search Tree

Day 9 Graph/BFS/DFS

Day 10 Dynamic Programming

Day 11 Dynamic Programming

Day 12 Sliding Window/Two Pointer

Day 13 Hashmap

0001	Two Sum	Data_Structure_I_Day_2_Array	Big_O_Time_O(n)_Space_O(n), AI_can_be_used_to_solve_the_task	2	99.56

Day 14 Stack

Day 15 Heap

Level 2

Day 1 Implementation/Simulation

Day 2 String

Day 3 Linked List

Day 4 Linked List

Day 5 Greedy

Day 6 Tree

Day 7 Tree

Day 8 Binary Search

Day 9 Binary Search Tree

Day 10 Graph/BFS/DFS

Day 11 Graph/BFS/DFS

Day 12 Dynamic Programming

Day 13 Dynamic Programming

Day 14 Sliding Window/Two Pointer

0003	Longest Substring Without Repeating Characters	Medium	Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Sliding_Window, Big_O_Time_O(n)_Space_O(1)	15	29.93

Day 15 Tree

Day 16 Design

Day 17 Interval

Day 18 Stack

Day 19 Union Find

Day 20 Brute Force/Backtracking

Udemy

Udemy Integers

Udemy Strings

0003	Longest Substring Without Repeating Characters	Medium	Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Sliding_Window, Big_O_Time_O(n)_Space_O(1)	15	29.93
0005	Longest Palindromic Substring	Medium	Top_100_Liked_Questions, Top_Interview_Questions, String, Dynamic_Programming, Big_O_Time_O(n)_Space_O(n)	2	97.74

Udemy Binary Search

Udemy Arrays

0001	Two Sum	Data_Structure_I_Day_2_Array	Big_O_Time_O(n)_Space_O(n), AI_can_be_used_to_solve_the_task	2	99.56

Udemy Two Pointers

Udemy Famous Algorithm

Udemy Sorting Algorithms

Udemy 2D Arrays/Matrix

Udemy Linked List

Udemy Tree Stack Queue

Udemy Trie and Heap

Udemy Graph

Udemy Dynamic Programming

Udemy Backtracking/Recursion

Udemy Bit Manipulation

Udemy Design

Algorithms

#	Title	Difficulty	Tag	Time, ms	Time, %
0005	Longest Palindromic Substring	Medium	Top_100_Liked_Questions, Top_Interview_Questions, String, Dynamic_Programming, Data_Structure_II_Day_9_String, Algorithm_II_Day_14_Dynamic_Programming, Dynamic_Programming_I_Day_17, Udemy_Strings, Big_O_Time_O(n)_Space_O(n)	2	97.74
0004	Median of Two Sorted Arrays	Hard	Top_100_Liked_Questions, Top_Interview_Questions, Array, Binary_Search, Divide_and_Conquer, Big_O_Time_O(log(min(N,M)))_Space_O(1)	0	100.00
0003	Longest Substring Without Repeating Characters	Medium	Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Sliding_Window, Algorithm_I_Day_6_Sliding_Window, Level_2_Day_14_Sliding_Window/Two_Pointer, Udemy_Strings, Big_O_Time_O(n)_Space_O(1)	15	29.93
0002	Add Two Numbers	Medium	Top_100_Liked_Questions, Top_Interview_Questions, Math, Linked_List, Recursion, Data_Structure_II_Day_10_Linked_List, Programming_Skills_II_Day_15, Big_O_Time_O(max(N,M))_Space_O(max(N,M)), AI_can_be_used_to_solve_the_task	12	70.50
0001	Two Sum	Data_Structure_I_Day_2_Array	Level_1_Day_13_Hashmap, Udemy_Arrays, Big_O_Time_O(n)_Space_O(n), AI_can_be_used_to_solve_the_task	2	99.56

Contributing

Your ideas/fixes/algorithms are more than welcome!

1. Fork this repo
2. Clone your forked repo (git clone https://github.com/YOUR_GITHUB_USERNAME/LeetCode-in-C.git) onto your local machine
3. cd into your cloned directory, create your feature branch (git checkout -b my-awesome-fix)
4. git add your desired changes to this repo
5. Commit your changes (git commit -m 'Added some awesome features/fixes')
6. Push to the branch (git push origin my-awesome-feature)
7. Open your forked repo on Github website, create a new Pull Request to this repo!