题目链接

层序遍历

思路：我们可以对二叉树进行层次遍历，那么对于每层来说，最右边的结点一定是最后被遍历到的。二叉树的层次遍历可以用广度优先搜索实现。

/*** Definition for a binary tree node.* public class TreeNode {*     int val;*     TreeNode left;*     TreeNode right;*     TreeNode() {}*     TreeNode(int val) { this.val = val; }*     TreeNode(int val, TreeNode left, TreeNode right) {*         this.val = val;*         this.left = left;*         this.right = right;*     }* }*/
class Solution {public List<Integer> rightSideView(TreeNode root) {List<Integer> list = new ArrayList();Deque<TreeNode> deque = new LinkedList<>();if(root != null){deque.offer(root);}while(!deque.isEmpty()){int size = deque.size();for(int i = 0; i < size; i++){TreeNode node = deque.poll();if(node.left != null){deque.offer(node.left);}if(node.right != null){deque.offer(node.right);} // 层序遍历到每一层的最后一个节点加入list数组if(i == size - 1){list.add(node.val);}}}return list;}
}