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  • 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?

    class Solution {
        public List<Integer> res = new ArrayList<>();
        public List<Integer> preorder(Node root) {
            if(root == null) return res;
            res.add(root.val);
            for(Node node : root.children) {
                preorder(node);
            }
            return res;
        }
    }
    /*
    // Definition for a Node.
    class Node {
        public int val;
        public List<Node> children;
    
        public Node() {}
    
        public Node(int _val,List<Node> _children) {
            val = _val;
            children = _children;
        }
    };
    */
    class Solution {
        public List<Integer> preorder(Node root) {
            List<Integer> res = new ArrayList<Integer>();
            preOrder(res,root);
            return res;
        }
        public void preOrder(List<Integer> res, Node root) {
            if(root == null) return;
            res.add(root.val);
            for(int i=0; i<root.children.size(); i++) {
                preOrder(res,root.children.get(i));
            }
        }
    }
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  • 原文地址:https://www.cnblogs.com/Roni-i/p/10456552.html
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