1+ """
2+ Problem Link: https://leetcode.com/problems/path-sum/
3+
4+ Given the root of a binary tree and an integer targetSum,
5+ return true if the tree has a root-to-leaf path such that adding up all
6+ the values along the path equals targetSum.
7+ A leaf is a node with no children.
8+
9+ Example 1:
10+ Input: root = [5,4,8,11,null,13,4,7,2,null,null,null,1], targetSum = 22
11+ Output: true
12+ Explanation: The root-to-leaf path with the target sum is shown.
13+
14+ Example 2:
15+ Input: root = [1,2,3], targetSum = 5
16+ Output: false
17+ Explanation: There two root-to-leaf paths in the tree:
18+ (1 --> 2): The sum is 3.
19+ (1 --> 3): The sum is 4.
20+ There is no root-to-leaf path with sum = 5.
21+
22+ Example 3:
23+ Input: root = [], targetSum = 0
24+ Output: false
25+ Explanation: Since the tree is empty, there are no root-to-leaf paths.
26+
27+ Constraints:
28+ The number of nodes in the tree is in the range [0, 5000].
29+ -1000 <= Node.val <= 1000
30+ -1000 <= targetSum <= 1000
31+ """
32+ # Definition for a binary tree node.
33+ # class TreeNode:
34+ # def __init__(self, val=0, left=None, right=None):
35+ # self.val = val
36+ # self.left = left
37+ # self.right = right
38+ class Solution :
39+ def hasPathSum (self , root : Optional [TreeNode ], targetSum : int ) -> bool :
40+ if not root :
41+ return False
42+ 43+ if targetSum - root .val == 0 and not root .left and not root .right :
44+ return True
45+ 46+ return self .hasPathSum (root .left , targetSum - root .val ) or self .hasPathSum (root .right , targetSum - root .val )
47+
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