This is a brief, cursory overview of the different Data Structures used in hw7:

1. array
   • Fixed size.
   • Once the array is full, cannot add unless you resize the array:
     1. Allocate a bigger array.
     2. Iterate through the original array and copy each element to the new memory.
     3. Update the reference to point to the new array.
   • Insert is expensive - need to iterate entire list and move each element down.
   • What about Delete?
   • What about Searching?
   • What about Sorting?
   • Uses a linear search function for insert and lookup, has O(n).

2. ArrayList
   • System manages memory for you, so can add as many as needed.
   • Insert is expensive - need to iterate entire list and move each element down.
   • What about Delete?
   • What about Searching?
   • What about Sorting?
   • Uses a linear search function for insert and lookup, has O(n).

3. HashMap
   • Key/Value pairs.
   • The key must be unique.
   • What about Delete?
   • What about Searching?
   • What about Sorting?
   • Uses a hashing function for insert and lookup, has O(1).

4. LinkedList
   • System manages memory for you, so can add as many as needed.
   • Only use as much memory as needed: each element has data and a next pointer (reference).
   • Insert is less expensive - need to iterate entire list until found, then just reset the next pointers (references).
   • What about Delete?
   • What about Searching?
   • What about Sorting?
   • Uses a linear search function for insert and lookup, has O(n).

5. Stack
   • Fixed size because typically implemented with an array.
   • Last-in-First-Out (LIFO).
   • Use push() to add an element onto the top of the stack.
   • Use pop() to retrieve the element at the top of the stack; the element is removed.