---
id: stack
title: Stack
---

- Implementation of an interpreter for a small language that does multiplication/addition/etc.
- Design a `MinStack` data structure that supports a `min()` operation that returns the minimum value in the stack in O(1) time.
- Write an algorithm to determine if all of the delimiters in an expression are matched and closed.
  - E.g. `{ac[bb]}`, `[dklf(df(kl))d]{}` and `{[[[]]]}` are matched. But `{3234[fd` and `{df][d}` are not.
  - [Source](http://blog.gainlo.co/index.php/2016/09/30/uber-interview-question-delimiter-matching/)
- Sort a stack in ascending order using an additional stack.