Binary tree per levels

Question

I must make a method that takes the variable "item" and put it in a string, for each element of the binary tree, but per levels..for example:
              1
   2     3               6
5                                4must return this string: 1 , 2 , 3 , 6 , 5 , 4
The tree is something like:
public class BinTree{
      private Node root;
      public class Node{
            public Node left;
            public Node right;
            public int item;
}Thank you very much :)

Answer 1

Sorry, I didn't specify: I can use recursion,Level order traversals are normally performed using a queue.
but in this case I don't know how to do it "per levels"..can
someone help me? Sure: use a queue and try to do it first on a pice of paper.
Also if you don't write the method,I won't. ; )
What would you learn from that? Perhaps a little, but you'll learn far more by doing it yourself.
just to tell me how to go through the tree in this
case. ThanksHere's some pseudo code:
LEVELORDER(root)
  queue.enqueue(root)
  WHILE queue not empty
    n = queue.dequeue()
    IF n.left  != null -> queue.enqueue(n.left )
    IF n.right != null -> queue.enqueue(n.right)
  END WHILE
END LEVELORDERAnd an example. Take the following tree:     5
  3     8
1   4 6   9No apply that pseudo code:
queue = new queue
queue.enqueue(5)
while(queue is not empty) {
  n = queue.dequeue() = 5
  n.left  != null, so queue.enqueue(3)
  n.irght != null, so queue.enqueue(8)
  (queue is now [3,8])
  n = queue.dequeue() = 3
  n.left  != null, so queue.enqueue(1)
  n.irght != null, so queue.enqueue(4)
  (queue is now [8,1,4])
  n = queue.dequeue() = 8
  n.left  != null, so queue.enqueue(6)
  n.irght != null, so queue.enqueue(9)
  (queue is now [1,4,6,9])
  n = queue.dequeue() = 1
  n.left  == null
  n.irght == null
  (queue is now [4,6,9])
  n = queue.dequeue() = 4
  n.left  == null
  n.irght == null
  (queue is now [6,9])
  n = queue.dequeue() = 6
  n.left  == null
  n.irght == null
  (queue is now [9]) 
  n = queue.dequeue() = 9
  n.left  == null
  n.irght == null
  (queue is now [])
  queue is empty, end while.
}As you can see, the items are dequeued in the following order: 5, 3, 8, 1, 4, 6, 9.
Good luck.