BallPath.java

import util.Point;

public class BallPath {

  // supports basic functionalities of an array list
  Point[] arr;
  int     color;

  int num, cap;

  public BallPath (int c, int cap) {

    color = c;
    this.cap = cap;

    // initialise the Path
    arr = new Point[cap];
    for (int i = 0; i < cap; i = i + 1) arr[i] = new Point(-1, -1);

  }

  public void increaseCap() {

    cap = 2 * (cap + 1);

    Point[] temp = new Point[cap];

    for (int i = 0;   i < num; i = i + 1) temp[i] = arr[i];
    for (int i = num; i < cap; i = i + 1) temp[i] = new Point(-1, -1);

    arr = temp;

  }

  public void add(Point P) {

    if (arr == null) return;

    if (num >= cap) increaseCap();

    arr[num] = P;
    num = num + 1;

  }

  // getters
  public int num() {

    return num;

  }

  public int color() {

    return color;

  }

  public Point get(int index) {

    if (index > num - 1) return null;

    return arr[index];

  }

}