Monday, July 21, 2014

Recursion Output



What is the output of the following program?
public class whatever {
    public static void main(String[] args) {
        xMethod(5);

    }
    public static void xMethod(int n){
        if (n>0){
            xMethod(n-1);
            System.out.print(n + " ");
        }
    }
}
main
   xMethod(5)
      xMethod(4)
          xMethod(3)
             xMethod(2)
                 xMethod(1)
                     xMethod(0)
                 print 1
             print 2
          print 3
      print 4
  print 5
So you see the prints are 1,2,3,4,5
System.out.print(n + " ");
xMethod(n-1);
It will print 5 4 3 2 1. Because It will first print then call xMethod.
And in your case
xMethod(n-1);
System.out.print(n + " ");
Here it will reach to end condition then poped up and print. so 1 2 3 4 5
Please read original article at Java - Understanding Recursion

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