[Head First Java] Chapter4 연습문제 수영장 퍼즐

코드 조각을 한번만 사용하여 아래와 같은 출력 결과를 얻어야 한다.
출력 결과

result 543345

문제

public class Puzzle4 {
	public static void main(String[] args) {
		________________________
		int y = 1;
		int x = 0;
		int result = 0;
		while(x < 6){
			________________
			________________
			y = y * 10;
			________
		}
		x = 6;
		while(x > 0){
			________
			result = result + ____________
		}
		System.out.println("result " + result);
	}
}
	
class ________{
	int ivar;
	________ doStuff(int ____){
		if(ivar > 100){
			return ________
		}
		else{
			return ________
		}
	}
}

코드 조각

ivar = x;
obs.ivar = x;
obs[x].ivar = x;
obs[x].ivar = y;

Puzzle4[] obs = new Puzzle4[6];
Puzzle4[] obs = new Puzzle4[6];
Puzzle4b[] obs = new Puzzle4b[6];
Puzzle4b[] obs = new puzzle4[6];

doStuff(x);
obs.doStuff(x);
obs[x].doStuff(factor);
obs[x].doStuff(x);

ivar
factor
public
private

ivar + factor;
ivar * (2 + factor);
ivar * (5 - factor);
ivar * factor;

x = x + 1;
x = x - 1;

Puzzle4
Puzzle4b
Puzzle4b()

int
short

obs[x] = new Puzzle4b(x);
obs[] = new Puzzle4b();
obs[x] = new Puzzle4b();
obs = new Puzzle4();

정답

public class Puzzle4 {
	public static void main(String[] args) {
		Puzzle4b[] obs = new Puzzle4b[6];
		int y = 1;
		int x = 0;
		int result = 0;
		while(x < 6){
			obs[x] = new Puzzle4b();
			obs[x].ivar = y;
			y = y * 10;
			x = x + 1;
		}
		x = 6;
		while(x > 0){
			x = x - 1;
			result = result + obs[x].doStuff(x);
		}
		System.out.println("result " + result);
	}
}
	
class Puzzle4b{
	int ivar;
	public int doStuff(int factor){
		if(ivar > 100){
			return ivar * factor;
		}
		else{
			return ivar * (5 - factor);
		}
	}
}

Puzzle4.java