Stacks & Queues

Brackets, monotonic stacks, queues and deques.

22 problems

Title	Tags	Acceptance	Difficulty
1. Stock Span	Monotonic Stack	—	Medium
2. First Unique After Each Step	Queue · Hash Map	—	Medium
3. Stack Operations	Stack	—	Easy
4. Queue Operations	Queue	—	Easy
5. Min Stack	Stack · Design	—	Medium
6. Evaluate Postfix Expression	Stack	—	Medium
7. Infix to Postfix	Stack · Shunting Yard	—	Medium
8. Next Greater Element (Circular)	Monotonic Stack	—	Medium
9. Largest Rectangle in a Histogram	Monotonic Stack	—	Hard
10. Remove K Digits	Monotonic Stack · Greedy	—	Medium
11. Asteroid Collision	Stack · Simulation	—	Medium
12. Sliding Window Minimum	Deque	—	Medium
13. Decode String	Stack · Parsing	—	Medium
14. Simplify Unix Path	Stack	—	Medium
15. Minimum Brackets to Add	Counting	—	Medium
16. Longest Valid Parentheses	Stack	—	Hard
17. First Negative in Every Window	Queue · Sliding Window	—	Easy
18. Binary Numbers 1 to N	Queue	—	Easy
19. The Celebrity	Stack · Elimination	—	Medium
20. Waiting Time at a Counter	Simulation	—	Medium
21. Basic Calculator	Parsing · Stack	—	Hard
22. Backspace String Compare	Stack · Two Pointers	—	Easy

22 of 22 problems