flexible-size list

/*
   GENERAL TASK DESCRIPTION

   Implement barebones (meaning - no getters/setters, or anything extraneous
   In task descriptions after data structure name the required interface (list of public methods) is in parentheses
   Use proper formatting. Implement each data structure in a separate class. For Node classes use inner classes.
   For brevity use primitive integer as value type (no generics).
*/

// Task 1 - singly-linked list (add, get, remove) add(), get(i), remove(i), remove(O)

// Task 2 - stack (push, pop)

// Task 3 - queue (offer, poll)

// Task 4 - flexible-size list (using arrays - think of ArrayList) - (add, get, remove, insert)


class MyList {

  private Integer[] arr;
  private int capacity;
  private int size;

  MyList(int capacity) {
    arr = new Integer[capacity];
    this.capacity = capacity;
  }

  public void add(Integer value) {
    if (size == capacity) {
      expandArray();
    }
    arr[++size - 1] = value; // size++ does the job
  }

  public Integer get(int idx) {
    if (ind < 0 || ind >= size)
      throw new ArrayIndexOutOfBounds();
    return arr[idx];
  }

  public Integer remove(int idx) {
     if (idx < 0 || idx >= size)
         throw new ArrayIndexOutOfBoundsException();

     Integer value = arr[idx];

     System.arraycopy(arr, idx + 1, arr, idx, size - idx - 1);
     arr[size - 1] = null;

     // 1 2 3 4 5
     // 1 2 4 5 5

     size--;

     return value;
  }

  public void insert(int idx, Integer value) {
    if (ind < 0 || ind >= size)
      throw new ArrayIndexOutOfBounds();

    if (size == capacity) {
      expandArray();
    }

    System.arraycopy(arr, idx, arr, idx + 1, size - idx);

    arr[idx] = value;
    size++;
  }

  private void expandArray() {
    Integer[] newArr = new Integer[capacity + capacity];
    System.arraycopy(arr, 0, newArr, 0, size);
    arr = newArr;
    capacity += capacity;
  }
}