public class App3 {
    public static void main(String[] args) {
        // Win + R -> calc

        SciCalc scicalc = new SciCalc();
        int i = scicalc.square(3);
        System.out.println(i);

        Calc calc = new Calc();
        i = calc.add(1,2);
        System.out.println(i);    

        //calc.square();  실행안됨

        ProgCalc progcalc = new ProgCalc();
        i = progcalc.sub(2,1);
        System.out.println(i);

        System.out.println();

        // 'Ctrl + /'
        calc.sub(4,2);
        scicalc.add(1,5);
        progcalc.add(4,4);

        // System.out.println(calc.recent);
        // System.out.println(scicalc.recent);
        // System.out.println(progcalc.recent);

        // SciCalcMk2 scicalcmk2 = new SciCalcMk2();

        // i = scicalcmk2.add(3,5);
        // System.out.println(i);

        // i = scicalcmk2.square(5);
        // System.out.println(i);

        progcalc.add(4, 3.5f);

        calc.recent(0);
        scicalc.recent(0);
        progcalc.recent(0);

        calc.recent(1);
        scicalc.recent(1);
        progcalc.recent(1);

        System.out.println(calc.numbering);
        System.out.println(scicalc.numbering);
    }
}


// Scientific Calculator is Calculator.
// Calculator has Memory

// Calc --> count = 2
// SciCalc --> count = 2

// Calc calc = new Calc()
// SciCalc scicalc = new SciCalc()

class Calc { //<-- 클래스
    static int count =0;
    int numbering;

    Calc(){
        count++;
        numbering = count;
    }

    // int recent = -1;
    Memory memory = new Memory();

    int add(int a, int b){
        String s = "" + a + "+" + b + "=" + (a+b);
        memory.update(s);
        return a+b;
    }

    // Overload 
    float add(float a, float b){
        String s = "" + a + " + " + b + " = " + (a+b);
        memory.update(s);
        return a + b;
    }

    int sub(int a, int b){
        String s = "" + a + "-" + b + "=" + (a-b);
        memory.update(s);
        return a-b;
    }

    void recent(int i){
        System.out.println(memory.recent[i]);
    }
}

class SciCalc extends Calc{
    int square(int a){
        String s = "" + a + "^2=" + (a*a);
        memory.update(s);

        return a*a;
    }
}

class SciCalcMk2 extends SciCalc{

}

class ProgCalc extends Calc{
    // Override
    @Override
    int add(int a, int b){
        String s = "" + a + " 더하기 " + b + " 는" + (a+b);
        memory.update(s);
        return a+b;
    }

    // Overload
    float add(int a ,float b){
        String s = "" + a + " 더하기 " + b + " 는" + (a+b);
        memory.update(s);
        return a+b;
    }
}
// 5, 3, 4
// 6
// 6, 5, 3
class Memory {
    String[] recent = new String[3];
    
    void update(String s){
        recent[2] = recent[1];
        recent[1] = recent[0];
        recent[0] = s;
    }
}

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