Please explain the output of the program.(how the algorithm is working?)

Question

public class Program
{
static void check(int y){
if(y>=0){
System.out.print(y+" ");
check(y-1);
System.out.print(y+" ");
}
}
public static void main(String[] args) {
check(3);
}
}

Answer 1

The output of this code will be :
32100123

Lets take a look at function check. It takes as parameter an integer y. If y is greater than 0, then print y and check for (y - 1). Then, it returns and print again y.

Example with 2
2 >= 0
print 2
(2 - 1) >= 0
print 1
(1 - 1) >= 0
print 0
(0 - 1) < 0
print 0
print 1
print 2