LeetCode_589.N叉树的前序遍历

给定一个 N 叉树，返回其节点值的前序遍历。

例如，给定一个 3叉树 :

返回其前序遍历: [1,3,5,6,2,4]。

说明: 递归法很简单，你可以使用迭代法完成此题吗?

/*
// Definition for a Node.
public class Node {
    public int val;
    public IList children;

    public Node() {}

    public Node(int _val) {
        val = _val;
    }

    public Node(int _val,IList _children) {
        val = _val;
        children = _children;
    }
}
*/

public class Solution {
    public IList Preorder(Node root) {
        IList list = new List();
        if(root == null) return list;

        Stack stack = new Stack();
        stack.Push(root);

        while(stack.TryPop(out Node node)){
            list.Add(node.val);
            int count = node.children.Count;
            while(--count > -1){
                stack.Push(node.children[count]);
            }
        }
        return list;
    }
}