1번

package prac;

class A {
	
	void method(int i) {
		System.out.println(i);
	}
	void method(int i, int j) {
		System.out.println(i * j);
	}
	
}

class B extends A {
	void method(int i, int j) {
		System.out.println(i * j);
	}
}

public class Test01 {

	public static void main(String[] args) {
		A a = new A();
		B b = new B();
		b.method(4,3);
		
	}

}

2번

package prac;

public class Test02 {
	public static void main(String[] args) {
		T1 t = new T1();
		t.myMethod();
	
	}
}

class T1 {
	void myMethod() {
		int x, y;
		x = 5; y = 3;
		System.out.println(x + ", " + y);
		switchCord(x, y);
		System.out.println(x + ", " + y);

	}
	
	void switchCord(int x, int y) {
		int temp;
		temp = x;
		x = y;
		y = temp;
		System.out.println(x + ", " + y);
	}
}

3번

package prac;

public class Test03 {

	public static void main(String[] args) {
		class Solution {
		    public double solution(int[] numbers) {
		        double answer = 0;
		        for(int i = 0; i < numbers.length; i++){
		            int x =+ numbers[i];
		            int y = numbers.length;
		            answer = x / y;
		        }
		        return answer;
		    }
		}
	}

}

4번

package prac;

public class Test04 {

	public static void main(String[] args) {
		int [] a = new int[1];
		modify(a);
		System.out.println(a[0]);
		

	}
     public static void modify(int[] a) {
    	 a[0]++;  // a[0] = a[0] + 1
     }
     
}

5번

package prac;

public class Test05 {

	public static void main(String[] args) {
		
		int a = 1;
		int b = a++;
		System.out.println(a);
		System.out.println(b);
		

		int c = 1;
		int d = 0;
		c++;
		d++;
		System.out.println(c);
		System.out.println(d++);
		
	}

}