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112_Path Sum.py
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44 lines (38 loc) · 1.26 KB
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# -*- coding: utf-8 -*-
"""
Created on Mon Jan 27 17:28:29 2020
@author: leiya
"""
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
'''
0721
'''
class Solution:
def hasPathSum(self, root: TreeNode, sum: int) -> bool:
def dfs(root,sum):
if not root:
return False
'''
注意符合要求的条件在于该node的左右都没有node了（意味着它是叶子节点，不加这个判断没办法确定是叶子节点）且他的值为sum
'''
if not root.left and not root.right and root.val == sum:
return True
else:
return dfs(root.left,sum-root.val) or dfs(root.right,sum-root.val)
if dfs(root,sum):
return True
else:
return False
class Solution:
def hasPathSum(self, root: TreeNode, sum: int) -> bool:
if root is None:
return False
if root.left is None and root.right is None and root.val == sum:
return True
else:
return self.hasPathSum(root.left,sum - root.val) or self.hasPathSum(root.right,sum-root.val)