Data Structures and Algorithms Training

This repository contains implementations or code segments of some classic data structures, algorithms and solutions of LeetCode questions.

Algorithms Training

Bubble Sort Algorithm:

• [C#] BubbleSortHelper

Merging Sort Algorithm:

• [C#] MergingSortHelper

Quick Sort Algorithm:

• [C#] QuickSortHelper

Insertion Sort Algorithm:

• [C#] InsertionSortHelper

Selection Sort Algorithm:

• [C#] SelectionSortHelper

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Data Structure

Link List:

• [C#] Link list definication
• [C#] Reverse logic

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LeetCode Questions:

LeetCode No.1 question: Two Sum

• [C#] Solution
• [C#] Official Answer

LeetCode No.2 question: Add Two Numbers

• [C#] Solution, the solution is INCORRECT since it cannot handle the big number, but I still keep it
• [C#] Official Answer

LeetCode No.3 question: Longest Substring without Repeating Characters

• [C#] Solution
• [C#] Official Answer

LeetCode No.4 question: Median of Two Sorted Arrays

• [C#] Solution A
• [C#] Solution B
• [C#] Official Answer A
• [C#] Official Answer B

LeetCode No.5 question: Longest Palindrome Substring

• [C#] Solution
• [C#] Official Answer A
• [C#] Official Answer B
• [C#] Official Answer C

LeetCode No.7 question: Reverse Integer

• [C#] Solution
• [C#] Official Answer

LeetCode No.8 question: String to Integer (atoi)

• [C#] Solution
• [C#] Official Answer

LeetCode No.9 question: Palindrome Number

• [C#] Solution
• [C#] Official Answer

LeetCode No.15 question: Three Sum

• [C#] Solution, the result is correct however the performance is very poor
• [C#] Official Answer

LeetCode No.16 question: Three Sum Closest

• [C#] Solution, the result is correct however the performance is very poor
• [C#] Official Answer

LeetCode No.17 question: Letter Combinations of a Phone Number

• [C#] Solution
• [C#] Official Answer

LeetCode No.18 question: Four Sum

• [C#] Solution, the result is correct however the performance is not good enough
• [C#] Official Answer

LeetCode No.20 question: Valid Parentheses

• [C#] Solution, the solution is as same as the official answer
• [C#] Official Answer

LeetCode No.21 question: Merge Two Sorted Lists

• [C#] Solution
• [C#] Official Answer
• [C#] Test Case, it costs a while to pass the unit test since I was blocked by pointer of linked list.

LeetCode No.23 question: Merge K Sorted Lists

• [C#] Solution A
• [C#] Solution B
• [C#] Official Answer A
• [C#] Official Answer B
• [C#] Official Answer C, this answer uses PriorityQueue, and PriorityQueue is just supported in .NET 6.