一种二叉树前序非递归遍历方法

1 class TreeNode(){
2 
3 　　public String data;
4 
5 　　public TreeNode leftChild;
6 
7 　　public TreeNode rightChild;
8 
9 }

 1 public void levelOrder3(TreeNode p){
 2     if(p == null) return ;
 3     Stack<TreeNode> stack = new Stack<TreeNode>();
 4     TreeNode node = p;
 5     stack.push(node);
 6     while(!stack.isEmpty()){
 7         node = stack.pop();
 8         visit(node);
 9         if(node.rightChild!= null) stack.push(node.rightChild);
10         if(node.leftChild != null) stack.push(node.leftChild);
11     }
12 }