Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.
For example:
Given the following binary tree,
1 <--- / 2 3 <--- \ 5 4 <---
You should return [1, 3, 4]
.
使用队列,层次遍历,每一层的最后一个节点。
/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public List<Integer> rightSideView(TreeNode root) { List<Integer> list = new ArrayList(); if (root == null){ return list; } Queue<TreeNode> queue = new LinkedList(); queue.add(root); while(!queue.isEmpty()){ int size = queue.size(); for (int i = 0; i < size; i++){ TreeNode node = queue.poll(); if (node.left != null){ queue.add(node.left); } if (node.right != null){ queue.add(node.right); } if (i == size - 1){ list.add(node.val); } } } return list; } }
时间: 2024-10-26 18:16:59