/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public List<Integer> rightSideView(TreeNode root) {
//思路:显然需要得到每一层的数据,用队列
List<Integer> retlist = new LinkedList<>();
if(root == null){
return retlist;
}
Queue<TreeNode> runningQueue = new LinkedList<>();
runningQueue.add(root);
while(!runningQueue.isEmpty()){
Queue<TreeNode> temrunningQueue = new LinkedList<>();
while(!runningQueue.isEmpty()){
TreeNode polltreenode = runningQueue.poll();
if(polltreenode.left!=null){
temrunningQueue.add(polltreenode.left);
}
if(polltreenode.right != null){
temrunningQueue.add(polltreenode.right);
}
if(runningQueue.isEmpty()){
retlist.add(polltreenode.val);
}
}
runningQueue = temrunningQueue;
}
return retlist;
}
}
没什么难度。使用queue记录每一层,然后找到最右侧的元素即可(被poll()的最后一个元素)