import tester.Tester;

interface IFunc<X, Y> {
  Y apply(X x);
}

// A function from Int -> Int that can be plotted on the cartesian plane
abstract class Plottable implements IFunc<Integer, Integer> {

  // Does this function cover the origin? (does f(0) = 0?)
  boolean coversOrigin() {
    return ...;
  }
}

// f(x) = x
class Identity extends Plottable {
  public Integer apply(Integer x) {
    return x;
  }
}
// f(x) = ax^2 + bx + c
class Quadratic extends Plottable {
  int a;
  int b;
  int c;

  Quadratic(int a, int b, int c) {
    this.a = a;
    this.b = b;
    this.c = c;
  }

  public Integer apply(Integer x) {
    return this.a * x * x + this.b * x + this.c;
  }
}

class ExamplesPlottable {
  Plottable identity = new Identity();
  Plottable xSquared = new Quadratic(1, 0, 0);
  Plottable xSquaredPlusOne = new Quadratic(1, 0, 1);

  boolean testIdentity(Tester t) {
    return t.checkExpect(identity.apply(0), ?)
        && t.checkExpect(identity.apply(5), ?);
  }

  boolean testXSquared(Tester t) {
    return t.checkExpect(xSquared.apply(0), ?)
        && t.checkExpect(xSquared.apply(5), ?);
  }

  boolean testXSquaredPlusOne(Tester t) {
    return t.checkExpect(xSquaredPlusOne.apply(0), ?)
        && t.checkExpect(xSquaredPlusOne.apply(5), ?);
  }

  boolean testCoversOrigin(Tester t) {
    return t.checkExpect(identity.coversOrigin(), ?)
        && t.checkExpect(xSquared.coversOrigin(), ?)
        && t.checkExpect(xSquaredPlusOne.coversOrigin(), ?);
  }
}