515. Find Largest Value in Each Tree Row 二叉树每一层的最大值

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

Example:

Input: 

          1
         / \
        3   2
       / \   \  
      5   3   9 

Output: [1, 3, 9]

题意：找出二叉树一层的最大值

解法：用BFS的方式遍历每一层

  1. class Solution(object):
  2.     def largestValues(self, root):
  3.         """
  4.         :type root: TreeNode
  5.         :rtype: List[int]
  6.         """
  7.         result = []
  8.         if not root:
  9.             return result
  10.         queue = [root]
  11.         while queue:
  12.             count = len(queue)
  13.             res = -2147483648
  14.             for i in range(count):
  15.                 curNode = queue.pop(0)
  16.                 res = max(curNode.val, res)
  17.                 if curNode.left:
  18.                     queue.append(curNode.left)
  19.                 if curNode.right:
  20.                     queue.append(curNode.right)
  21.             result.append(res)
  22.         return result







posted @ 2017-08-19 20:56  xiejunzhao  阅读(576)  评论(0)  编辑  收藏  举报