Find Largest Value in Each Tree Row

You need to find the largest value in each row of a binary tree.

BFS

Time Complexity

思路

简单的BFS，每层更新最大值放入res

代码

public List
    
      largestValues(TreeNode root) {    List
     
       res = new ArrayList
      
       ();    if(root == null) return res;    Queue
       
         queue = new LinkedList
        
         ();    queue.offer(root);    while(!queue.isEmpty()){        int size = queue.size();        int max = Integer.MIN_VALUE;        for(int i = 0; i < size; i++){            TreeNode cur = queue.poll();            max = Math.max(cur.val, max);            if(cur.left != null){                queue.offer(cur.left);            }            if(cur.right != null){                queue.offer(cur.right);            }        }        res.add(max);    }    return res;}