二叉树的反向级别遍历

class Node {
     int data;
    Node left, right;

   Node(int item) {
      data = item;
     left = right = null;
    }
   }

   public class BinaryTree {
     Node root;

  /* Function to print REVERSE level order traversal a tree */
     public void reverseLevelOrder(Node node) {
    int h = height(node);
    int i;
   for (i = h; i >= 1; i--)
      // THE ONLY LINE DIFFERENT FROM NORMAL LEVEL ORDER
   {
     printGivenLevel(node, i);
   }
   }

   /* Print nodes at a given level */
   public void printGivenLevel(Node node, int level) {
   if (node == null)
     return;
     if (level == 1)
       System.out.print(node.data + " ");
      else if (level > 1) {
      printGivenLevel(node.left, level - 1);
       printGivenLevel(node.right, level - 1);
     }
   }

   /*
    * Compute the "height" of a tree -- the number of nodes along the longest
    * path from the root node down to the farthest leaf node.
    */
  int height(Node node) {
   if (node == null)
     return 0;
   else {
    /* compute the height of each subtree */
     int lheight = height(node.left);
     int rheight = height(node.right);

       /* use the larger one */
     if (lheight > rheight)
     return (lheight + 1);
       else
      return (rheight + 1);
      }
   }

   // Driver program to test above functions
    public static void main(String args[]) {
      
     BinaryTree tree = new BinaryTree();

     // Let us create trees shown in above diagram
    tree.root = new Node(1);
     tree.root.left = new Node(2);
    tree.root.right = new Node(3);
   tree.root.left.left = new Node(4);
   tree.root.left.right = new Node(5);
      tree.reverseLevelOrder(tree.root);

      
    }
}