leetcode算法: Find Bottom Left Tree Value Given a binary tree, find the leftmost value in the last row of the tree. Example 1: Input: 2 / \ 1 3 Output: 1 Example 2: Input: 1 / \ 2 3 / / \ 4 5 6 / 7 Output: 7 Note: You may assume the tree (i.e., the given root node) is not NULL. 这道题 是 给我们一颗二叉树的根节点,让我们找到最后一层的最左边的节点。 绞尽脑汁之后,利用二维数组把每个节点和所在层次扒下来了,但是还是太麻烦。看了其他大神的思路豁然开朗! 大神的思路是:从右向左广度优先遍历!! 最后一个节点就是我们要的结果!! 献上我的代码:
1 # Definition for a binary tree node. 2 # class TreeNode(object): 3 # def __init__(self, x): 4 # self.val = x 5 # self.left = None 6 # self.right = None 7 8 class Solution(object): 9 def findBottomLeftValue(self, root):10 """11 :type root: TreeNode12 :rtype: int13 """14 q = [root]15 while q:16 node = q.pop(0)17 if node.right is not None:18 q.append(node.right)19 if node.left is not None:20 q.append(node.left)21 return node.val