LeetCode -- Binary Tree Preorder Traversal

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left;
 *     public TreeNode right;
 *     public TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public IList<int> PreorderTraversal(TreeNode root) 
    {
        var ret = new List<int>();
    	Travel(root, ref ret);
    	
    	return ret;
    }


private void Travel(TreeNode current, ref List<int> result)
{
	if(current == null){
		return ;
	}
	result.Add(current.val);
	
	Travel(current.left, ref result);
	Travel(current.right, ref result);
}
}

LeetCode -- Binary Tree Preorder Traversal

原文：http://blog.csdn.net/lan_liang/article/details/49188153