题目
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.
难度
Medium
方法
通过使用队列后续遍历二叉树，队列中的最后一个节点即为二叉树最后一行的最左节点
python代码
from Queue import Queue
class TreeNode(object):
def __init__(self, x):
self.val = x
self.left = None
self.right =None
class Solution(object):
def findBottomLeftValue(self, root):
"""
:type root: TreeNode
:rtype int
"""
queue = Queue()
queue.put(root)
node = None
while not queue.empty():
node = queue.get()
if node.right:
queue.put(node.right)
if node.left:
queue.put(node.left)
return node.val
root = TreeNode(2)
left = TreeNode(1)
right = TreeNode(3)
root.left = left
root.right = right
Solution().findBottomLeftValue(root) == 1
root = TreeNode(1)
node1_1 = TreeNode(2)
node1_2 = TreeNode(3)
node2_1 = TreeNode(4)
node2_2 = TreeNode(5)
node2_3 = TreeNode(6)
node3_1 = TreeNode(7)
root.left = node1_1
root.right = node1_2
node1_1.left = node2_1
node1_2.left = node2_2
node1_2.right = node2_3
node2_2.left = node3_1
Solution().findBottomLeftValue(root) == 7
