# Chapter 1

## Efficiency

Concerns:
1. Number of operations
2. Processor speeds
3. Storage space

## Interfaces

* Interface / abstract data type

### Queue interface

* `add(x)` (aka `queue`): add `x` to the queue
* `remove()` (aka `dequeue`): remove the next value from queue and return it

* Normal queue: the first element inserted is removed first
* Priority queue: elements are inserted with a priority, and the smallest
  element is removed. This function is usually called `deleteMin`.
* LIFO queue: a stack; add and remove are called `push` and `pop`.