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LeetCode112.路径总和

version 1

# Definition for a binary tree node.class TreeNode:    def __init__(self, x):        self.val = x        self.left = None        self.right = Noneclass Solution:    def __init__(self):        self.hasFind = False        self.target = None    def hasPathSum(self, root, sum):        """        :type root: TreeNode        :type sum: int        :rtype: bool        """        if not root: return False        self.target = sum        self.dfs(root, root.val)        return self.hasFind    def dfs(self, bt: TreeNode, s):        if self.hasFind:            return        if s == self.target and not bt.left and not bt.right:            self.hasFind = True            return        if bt.left:            self.dfs(bt.left, s + bt.left.val)        if bt.right:            self.dfs(bt.right, s + bt.right.val)

version 2

# Definition for a binary tree node.class TreeNode:    def __init__(self, x):        self.val = x        self.left = None        self.right = Noneclass Solution:    def hasPathSum(self, root, sum):        """        :type root: TreeNode        :type sum: int        :rtype: bool        """        if not root: return False        elif root.val == sum and not root.left and not root.right:            return True        return self.hasPathSum(root.left, sum - root.val) or self.hasPathSum(root.right, sum - root.val)

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