[Leetcode] (Python): the Path Sum

Source of the topic

https://leetcode.com/problems/path-sum/

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such this adding up all the values along the Path equals the given sum.

Test instructions Analysis

input:a binary tree, sum

Output:true or False

Conditions: Determine if there is a path from the path of root-leaf, so that the sum of the value of the path is equal to sums

Topic ideas

Recursive traversal, judged by a constant descending sum value.

AC Code (PYTHON)

1 #Definition for a binary tree node.2 #class TreeNode (object):3 #def __init__ (self, x):4 #self.val = x5 #self.left = None6 #self.right = None7 8 classsolution (object):9     defhaspathsum (self, Root, sum):Ten         """ One : Type Root:treenode A : Type Sum:int - : Rtype:bool -         """ the         ifRoot = =None: -             returnFalse -         ifRoot.left = = None andRoot.right = =None: -             returnRoot.val = =sum +         returnSelf.haspathsum (Root.left, Sum-root.val)orSelf.haspathsum (root.right, Sum-root.val) -         

[Leetcode] (Python): the Path Sum