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111.py
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111.py
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# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def minDepth(self, root):
"""
:type root: TreeNode
:rtype: int
"""
if not root:
return 0
depth = [99999999] # 为何depth = 999999,就不能访问
def preorder(node, dep):
if node:
dep += 1
if node.left:
preorder(node.left, dep)
if node.right:
preorder(node.right, dep)
if (not node.left) and (not node.right) and dep < depth[0]:
depth[0] = dep
preorder(root, 0)
return depth[0]
# 这种解法更符合tree的思想,上面遍历太傻了
def minDepth(self, root):
if not root:
return 0
if not root.left or not root.right: # 左右节点有一个有值,那该节点的dep等于大的
return max(self.minDepth(root.left), self.minDepth(root.right)) + 1
else: # 左右都非空,取小的
return min(self.minDepth(root.left), self.minDepth(root.right)) + 1