Average value by level in a tree
/**
* 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<List<Integer>> levelOrder(TreeNode root) {
List<List<Integer>> res=new LinkedList<>();
if(root==null) return res;
Queue<TreeNode> queue=new LinkedList<>();
queue.offer(root);
while(!queue.isEmpty()){
int size=queue.size();
List<Integer> list=new LinkedList<>();
for(int i=0;i<size;i++){
TreeNode cur=queue.poll();
list.add(cur.val);
if(cur.left!=null) queue.offer(cur.left);
if(cur.right!=null) queue.offer(cur.right);
}
res.add(list);
}
return res;
}
}
