# LeetCode 707. Design Linked List

Description https://leetcode.com/problems/design-linked-list/ Design your implementation of the linked list. You can choose to use the singly linked list or the doubly…

# LeetCode 70. Climbing Stairs

Description https://leetcode.com/problems/climbing-stairs/ You are climbing a stair case. It takes n steps to reach to the top. Each time you can either…

# LeetCode 547. Friend Circles

Description https://leetcode.com/problems/friend-circles/description/ There are N students in a class. Some of them are friends, while some are not. Their friendship is transitive…

# LeetCode 387. First Unique Character in a String

Description https://leetcode.com/problems/first-unique-character-in-a-string/description/ Given a string, find the first non-repeating character in it and return it’s index. If it doesn’t exist,…

# LeetCode 84. Largest Rectangle in Histogram

Description https://leetcode.com/problems/largest-rectangle-in-histogram/description/ Given n non-negative integers representing the histogram’s bar height where the width of each bar is 1, find the area…