Counting numbers up and down using Recursion

Question

Given two numbers, let\'s say start = 1 and end = 4, I am trying to count all the numbers in sequence up and then down . No looping is allowed

Answer 1

You just have to use the recursion for counting up. Then, when the function returns, you are on your way down. This can be achieved with:

public void countUpAndDown(int start, int end) {
    System.out.println(start);
    if (end == start) return;
    countUpAndDown(start+1, end);
    System.out.println(start);
}