5. 별(1→5/오른쪽정렬)

풀이

1) 노가다

package ex03;

public class Test5Me {
    public static void main(String[] args) {

        System.out.print(" ");
        System.out.print(" ");
        System.out.print(" ");
        System.out.print(" ");
        System.out.print("*");
        System.out.println();

        System.out.print(" ");
        System.out.print(" ");
        System.out.print(" ");
        System.out.print("*");
        System.out.print("*");
        System.out.println();

        System.out.print(" ");
        System.out.print(" ");
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.println();

        System.out.print(" ");
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.println();

        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.println();
    }
}

2) 공란→for문/별→노가다

package ex03;

public class Test51Me {
    public static void main(String[] args) {
        int x = 5;
        int y = 0;

        for (int i = 0; i < 4; i++) {
            System.out.print(" ");
        }
        System.out.print("*");
        System.out.println();

        for (int i = 0; i < 3; i++) {
            System.out.print(" ");
        }
        System.out.print("*");
        System.out.print("*");
        System.out.println();

        for (int i = 0; i < 2; i++) {
            System.out.print(" ");
        }
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.println();

        for (int i = 0; i < 1; i++) {
            System.out.print(" ");
        }
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.println();

        for (int i = 0; i < 0; i++) {
            System.out.print(" ");
        }
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.print("*");
        System.out.println();
    }
}

3) for문 정리 1

package ex03;

public class Test52Me {
    public static void main(String[] args) {

        for (int i = 0; i < 4; i++) {
            System.out.print(" ");
        }
        for (int j = 0; j < 1; j++) {
            System.out.print("*");
        }
        System.out.println();

        for (int i = 0; i < 3; i++) {
            System.out.print(" ");
        }
        for (int j = 0; j < 2; j++) {
            System.out.print("*");
        }
        System.out.println();

        for (int i = 0; i < 2; i++) {
            System.out.print(" ");
        }
        for (int j = 0; j < 3; j++) {
            System.out.print("*");
        }
        System.out.println();

        for (int i = 0; i < 1; i++) {
            System.out.print(" ");
        }
        for (int j = 0; j < 4; j++) {
            System.out.print("*");
        }
        System.out.println();

        for (int i = 0; i < 0; i++) {
            System.out.print(" ");
        }
        for (int j = 0; j < 5; j++) {
            System.out.print("*");
        }
        System.out.println();
    }
}

4) for문 정리 2

package ex03;

public class Test53Me {
    public static void main(String[] args) {
        int x = 5;
        int y = 0;

        x--;
        for (int i = 0; i < x; i++) {
            System.out.print(" ");
        }
        y++;
        for (int j = 0; j < y; j++) {
            System.out.print("*");
        }
        System.out.println();

        x--;
        for (int i = 0; i < x; i++) {
            System.out.print(" ");
        }
        y++;
        for (int j = 0; j < y; j++) {
            System.out.print("*");
        }
        System.out.println();

        x--;
        for (int i = 0; i < x; i++) {
            System.out.print(" ");
        }
        y++;
        for (int j = 0; j < y; j++) {
            System.out.print("*");
        }
        System.out.println();

        x--;
        for (int i = 0; i < x; i++) {
            System.out.print(" ");
        }
        y++;
        for (int j = 0; j < y; j++) {
            System.out.print("*");
        }
        System.out.println();

        x--;
        for (int i = 0; i < x; i++) {
            System.out.print(" ");
        }
        y++;
        for (int j = 0; j < y; j++) {
            System.out.print("*");
        }
        System.out.println();
    }
}

5) for문 정리 3

package ex03;

public class Test54Me {
    public static void main(String[] args) {
        int x = 5;
        int y = 0;

        for (int k = 0; k < 5; k++) {
            x--;
            for (int i = 0; i < x; i++) {
                System.out.print(" ");
            }
            y++;
            for (int j = 0; j < y; j++) {
                System.out.print("*");
            }
            System.out.println();
        }
    }
}

6) for문 정리 4

package ex03;

public class Test5Me5 {
    public static void main(String[] args) {
        int x = 5;
        int y = 5;
        int z = 0;

        for (int k = 0; k < x; k++) {
            y--;
            for (int i = 0; i < y; i++) {
                System.out.print(" ");
            }
            z++;
            for (int j = 0; j < z; j++) {
                System.out.print("*");
            }
            System.out.println();
        }
    }
}

7) 결과

정답(3행)

1) 노가다

package ex03;

public class Test5T {
    public static void main(String[] args) {
        String space = " ";
        String star = "*";

        // 1행 (space, space, star)
        System.out.print(space);
        System.out.print(space);
        System.out.print(star);
        System.out.println();

        // 2행 (space, star, star)
        System.out.print(space);
        System.out.print(star);
        System.out.print(star);
        System.out.println();

        // 3행 (star, star, star)
        System.out.print(star);
        System.out.print(star);
        System.out.print(star);
        System.out.println();

    }
}

2) for문 1차 정리

package ex03;

public class Test5T {
    public static void main(String[] args) {
        String space = " ";
        String star = "*";

        // 1행 (space, space, star)
        for (int i = 0; i < 2; i++) {
            System.out.print(space);
        }
        for (int i = 0; i < 1; i++) {
            System.out.print(star);
        }
        System.out.println();

        // 2행 (space, star, star)
        for (int i = 0; i < 1; i++) {
            System.out.print(space);
        }
        for (int i = 0; i < 2; i++) {
            System.out.print(star);
        }
        System.out.println();

        // 3행 (star, star, star)
        for (int i = 0; i < 0; i++) {
            System.out.print(space);
        }
        for (int i = 0; i < 3; i++) {
            System.out.print(star);
        }
        System.out.println();

    }
}

3) 변수 정리

package ex03;

public class Test5T {
    public static void main(String[] args) {
        String space = " ";
        String star = "*";
        int n1 = 2;
        int n2 = 1;

        // 1행 (space, space, star)
        for (int i = 0; i < n1; i++) {
            System.out.print(space);
        }
        for (int i = 0; i < n2; i++) {
            System.out.print(star);
        }
        System.out.println();
        n1--;
        n2++;

        // 2행 (space, star, star)
        for (int i = 0; i < n1; i++) {
            System.out.print(space);
        }
        for (int i = 0; i < n2; i++) {
            System.out.print(star);
        }
        System.out.println();
        n1--;
        n2++;

        // 3행 (star, star, star)
        for (int i = 0; i < n1; i++) {
            System.out.print(space);
        }
        for (int i = 0; i < n2; i++) {
            System.out.print(star);
        }
        System.out.println();
        n1--;
        n2++;

    }
}

4) for문 2차 정리

package ex03;

public class Test5T {
    public static void main(String[] args) {
        String space = " ";
        String star = "*";
        int n1 = 2;
        int n2 = 1;

        for (int k = 0; k < 3; k++) {
            for (int i = 0; i < n1; i++) {
                System.out.print(space);
            }
            for (int i = 0; i < n2; i++) {
                System.out.print(star);
            }
            System.out.println();
            n1--;
            n2++;
        }


    }
}

5) 최종 정리(변수의 수 최소화)

package ex03;

public class Test5T {
    public static void main(String[] args) {
        // 3행 - space2, star1
        // 4행 - space3, star1
        // 5행 - space4, star1
        // star 1로 고정 -> 상수
        // space = 행 - 1

        String space = " ";
        String star = "*";
        int row = 3;        //행수
        int n1 = row-1;     //space 수
        int n2 = 1;         // star 수

        for (int k = 0; k < row; k++) {
            for (int i = 0; i < n1; i++) {
                System.out.print(space);
            }
            for (int i = 0; i < n2; i++) {
                System.out.print(star);
            }
            System.out.println();
            n1--;
            n2++;
        }


    }
}

6) 결과