function extend(Child, Parent) {

    var F = function() { };

    F.prototype = Parent.prototype;

    Child.prototype = new F();

    Child.prototype.constructor = Child;

    Child.superclass = Parent.prototype;

}

​

function rand(min, max) {

    if( max ) {

        return Math.floor(Math.random() * (max - min + 1)) + min;

    } else {

        return Math.floor(Math.random() * (min + 1));

    }

}

​

​

function PowerGrid() {

}

​

function PowerPlant() {

    this.power = 0;

}

​

extend(PowerPlant, PowerGrid);

​

PowerPlant.prototype.setPower = function() {

    this.power = rand(1, 100);

};

​

function SolarPanel(isDay) {

    this.isDay = isDay;

    this.power = 0;

}

​

extend(SolarPanel, PowerGrid);

​

SolarPanel.prototype.setPower = function() {

    if (isDay) {

        this.power = rand(1, 5);

    } else {

        this.power = 0;

    }

};

​

function House(flats, isDay) {

    this.flats = 0;

    this.isDay = isDay;

    this.power = 0;

}

​

extend(House, PowerGrid);

​

House.prototype.setPower = function() {

    if (this.isDay) {

        return 0.004;

    } else {

        return 0.001;

    }

};

​

House.prototype.setFlats = function() {

    this.flats = rand(1, 400);

};

​

function ElLines(power, price) {

    this.power = 0;

    this.price = 0;

}

​

extend(ElLines, PowerGrid);

​

ElLines.prototype.setPower = function() {

    this.power = rand(10, 80);

    this.price = rand(1, 10);

};

​

function City() {

}

​

​

​

​

​