Algorithms

LeetCode solutions in C focused on algorithms, data structures, and problem solving.

LeetCode Topics

Array

Problem Name	Difficulty
0001-two-sum	Easy
0014-longest-common-prefix	Easy
0026-remove-duplicates-from-sorted-array	Easy
0027-remove-element	Easy
0035-search-insert-position	Easy
0066-plus-one	Easy
0075-sort-colors	Medium
0088-merge-sorted-array	Easy
0136-single-number	Easy
0169-majority-element	Easy
0217-contains-duplicate	Easy
0268-missing-number	Easy
0349-intersection-of-two-arrays	Easy
0414-third-maximum-number	Easy
0448-find-all-numbers-disappeared-in-an-array	Easy
0539-minimum-time-difference	Medium
0643-maximum-average-subarray-i	Easy
0704-binary-search	Easy
0977-squares-of-a-sorted-array	Easy
1431-kids-with-the-greatest-number-of-candies	Easy
1662-check-if-two-string-arrays-are-equivalent	Easy

Hash Table

Problem Name	Difficulty
0001-two-sum	Easy
0003-longest-substring-without-repeating-characters	Medium
0012-integer-to-roman	Medium
0013-roman-to-integer	Easy
0169-majority-element	Easy
0217-contains-duplicate	Easy
0242-valid-anagram	Easy
0268-missing-number	Easy
0349-intersection-of-two-arrays	Easy
0383-ransom-note	Easy
0389-find-the-difference	Easy
0448-find-all-numbers-disappeared-in-an-array	Easy
1370-increasing-decreasing-string	Easy

Two Pointers

Problem Name	Difficulty
0026-remove-duplicates-from-sorted-array	Easy
0027-remove-element	Easy
0028-find-the-index-of-the-first-occurrence-in-a-string	Easy
0075-sort-colors	Medium
0088-merge-sorted-array	Easy
0125-valid-palindrome	Easy
0344-reverse-string	Easy
0349-intersection-of-two-arrays	Easy
0876-middle-of-the-linked-list	Easy
0977-squares-of-a-sorted-array	Easy

Sorting

Problem Name	Difficulty
0075-sort-colors	Medium
0088-merge-sorted-array	Easy
0169-majority-element	Easy
0217-contains-duplicate	Easy
0242-valid-anagram	Easy
0268-missing-number	Easy
0349-intersection-of-two-arrays	Easy
0389-find-the-difference	Easy
0414-third-maximum-number	Easy
0539-minimum-time-difference	Medium
0977-squares-of-a-sorted-array	Easy

String

Problem Name	Difficulty
0003-longest-substring-without-repeating-characters	Medium
0012-integer-to-roman	Medium
0013-roman-to-integer	Easy
0014-longest-common-prefix	Easy
0020-valid-parentheses	Easy
0028-find-the-index-of-the-first-occurrence-in-a-string	Easy
0058-length-of-last-word	Easy
0067-add-binary	Easy
0125-valid-palindrome	Easy
0242-valid-anagram	Easy
0344-reverse-string	Easy
0383-ransom-note	Easy
0389-find-the-difference	Easy
0539-minimum-time-difference	Medium
0657-robot-return-to-origin	Easy
0796-rotate-string	Easy
0921-minimum-add-to-make-parentheses-valid	Medium
1021-remove-outermost-parentheses	Easy
1209-remove-all-adjacent-duplicates-in-string-ii	Medium
1370-increasing-decreasing-string	Easy
1544-make-the-string-great	Easy
1662-check-if-two-string-arrays-are-equivalent	Easy

Stack

Problem Name	Difficulty
0020-valid-parentheses	Easy
0921-minimum-add-to-make-parentheses-valid	Medium
1021-remove-outermost-parentheses	Easy
1209-remove-all-adjacent-duplicates-in-string-ii	Medium
1544-make-the-string-great	Easy

Bracket Sequences

Problem Name	Difficulty
0020-valid-parentheses	Easy
0921-minimum-add-to-make-parentheses-valid	Medium
1021-remove-outermost-parentheses	Easy

Linked List

Problem Name	Difficulty
0002-add-two-numbers	Medium
0021-merge-two-sorted-lists	Easy
0023-merge-k-sorted-lists	Hard
0024-swap-nodes-in-pairs	Medium
0083-remove-duplicates-from-sorted-list	Easy
0203-remove-linked-list-elements	Easy
0206-reverse-linked-list	Easy
0237-delete-node-in-a-linked-list	Medium
0876-middle-of-the-linked-list	Easy

Math

Problem Name	Difficulty
0002-add-two-numbers	Medium
0009-palindrome-number	Easy
0012-integer-to-roman	Medium
0013-roman-to-integer	Easy
0066-plus-one	Easy
0067-add-binary	Easy
0069-sqrtx	Easy
0070-climbing-stairs	Easy
0268-missing-number	Easy
0367-valid-perfect-square	Easy
0539-minimum-time-difference	Medium

Recursion

Problem Name	Difficulty
0002-add-two-numbers	Medium
0021-merge-two-sorted-lists	Easy
0024-swap-nodes-in-pairs	Medium
0203-remove-linked-list-elements	Easy
0206-reverse-linked-list	Easy

Trie

Problem Name	Difficulty
0014-longest-common-prefix	Easy

String Matching

Problem Name	Difficulty
0028-find-the-index-of-the-first-occurrence-in-a-string	Easy
0796-rotate-string	Easy

Z Algorithm

Problem Name	Difficulty
0028-find-the-index-of-the-first-occurrence-in-a-string	Easy

Knuth–Morris–Pratt Algorithm

Problem Name	Difficulty
0028-find-the-index-of-the-first-occurrence-in-a-string	Easy

Boyer–Moore String-Search Algorithm

Problem Name	Difficulty
0028-find-the-index-of-the-first-occurrence-in-a-string	Easy

Binary Search

Problem Name	Difficulty
0035-search-insert-position	Easy
0069-sqrtx	Easy
0268-missing-number	Easy
0349-intersection-of-two-arrays	Easy
0367-valid-perfect-square	Easy
0704-binary-search	Easy

Newton's Method

Problem Name	Difficulty
0069-sqrtx	Easy

Dynamic Programming

Problem Name	Difficulty
0070-climbing-stairs	Easy

Memoization

Problem Name	Difficulty
0070-climbing-stairs	Easy

Tree

Problem Name	Difficulty
0100-same-tree	Easy

Depth-First Search

Problem Name	Difficulty
0100-same-tree	Easy
0547-number-of-provinces	Medium

Breadth-First Search

Problem Name	Difficulty
0100-same-tree	Easy
0547-number-of-provinces	Medium

Binary Tree

Problem Name	Difficulty
0100-same-tree	Easy

Counting

Problem Name	Difficulty
0169-majority-element	Easy
0383-ransom-note	Easy
1370-increasing-decreasing-string	Easy

Simulation

Problem Name	Difficulty
0067-add-binary	Easy
0657-robot-return-to-origin	Easy

Bit Manipulation

Problem Name	Difficulty
0067-add-binary	Easy
0136-single-number	Easy
0190-reverse-bits	Easy
0191-number-of-1-bits	Easy
0268-missing-number	Easy
0389-find-the-difference	Easy

Sliding Window

Problem Name	Difficulty
0003-longest-substring-without-repeating-characters	Medium
0643-maximum-average-subarray-i	Easy

Quicksort

Problem Name	Difficulty
0075-sort-colors	Medium

Bubble Sort

Problem Name	Difficulty
0075-sort-colors	Medium

Divide and Conquer

Problem Name	Difficulty
0023-merge-k-sorted-lists	Hard
0169-majority-element	Easy
0190-reverse-bits	Easy
0191-number-of-1-bits	Easy

Union-Find

Problem Name	Difficulty
0547-number-of-provinces	Medium

Graph Theory

Problem Name	Difficulty
0547-number-of-provinces	Medium

Greedy

Problem Name	Difficulty
0921-minimum-add-to-make-parentheses-valid	Medium

Boyer–Moore Majority Vote Algorithm

Problem Name	Difficulty
0169-majority-element	Easy

Heap (Priority Queue)

Problem Name	Difficulty
0023-merge-k-sorted-lists	Hard

Merge Sort

Problem Name	Difficulty
0023-merge-k-sorted-lists	Hard

Tournament Sort

Problem Name	Difficulty
0023-merge-k-sorted-lists	Hard

Database

Problem Name	Difficulty
0175-combine-two-tables	Easy
0178-rank-scores	Medium
0181-employees-earning-more-than-their-managers	Easy
0183-customers-who-never-order	Easy
0511-game-play-analysis-i	Easy
0577-employee-bonus	Easy

Contact & Support

Trieu Ha Giang - Embedded Systems Engineering Student

Thank you for visiting this repository.
If you have any questions or feedback, feel free to reach out directly.

My contact: