Algorithm Analysis

Let's use a for loop. We'll iterate through all the numbers from $b$ to $a$ in descending order and print the even ones.

Algorithm Implementation

Read the input data.

scanf("%d %d", &a, &b);

Iterate through the numbers from $b$ to $a$ in descending order and print the even ones.

for (i = b; i >= a; i--)
    if (i % 2 == 0)
        printf("%d ", i);

Java Implementation

import java.util.*;

class Main
{
    public static void main(String[] args)
    {
        Scanner con = new Scanner(System.in);
        int a = con.nextInt();
        int b = con.nextInt();
        for(int i = b; i >= a; i--)
            if (i % 2 == 0)
                System.out.print(i + " ");
        con.close();
    }
}

Python Implementation

Read the input data.

a, b = map(int, input().split())

Iterate through the numbers from $b$ to $a$ in descending order and print the even ones.

for i in range(b, a - 1, -1):
    if i % 2 == 0: 
        print(i, end=" ")