Path Sum III
Given the root of a binary tree and an integer targetSum, return the number of paths where the sum of the values along the path equals targetSum.
The path does not need to start or end at the root or a leaf, but it must go downwards, meaning it travels only from parent nodes to child nodes.
Example 1
10
/ \
5 -3
/ \ \
3 2 11
/ \ \
3 -2 1Input
root = [10,5,-3,3,2,null,11,3,-2,null,1], targetSum = 8Output
3There are three downward paths whose values sum to 8.
Example 2
5
/ \
4 8
/ / \
11 13 4
/ \ / \
7 2 5 1Input
root = [5,4,8,11,null,13,4,7,2,null,null,5,1], targetSum = 22Output
3There are three downward paths whose values sum to 22.
Constraints
- The number of nodes in the tree is in the range
[0, 1000]. -10^9 <= Node.val <= 10^9-1000 <= targetSum <= 1000