You are given a binary tree in which each node contains an integer value.
- Find the number of paths that sum to a given value.
- The path does not need to start or end at the root or a leaf, but it must go downwards (traveling only from parent nodes to child nodes).
- The tree has no more than 1,000 nodes and the values are in the range -1,000,000 to 1,000,000.
- Example:
- root = [10,5,-3,3,2,null,11,3,-2,null,1], sum = 8
- 10
- / 5 -3
- / \ 3 2 11
- / \ 3 -2 1
- Return 3. The paths that sum to 8 are:
- 1. 5 -> 3
- 2. 5 -> 2 -> 1
- 3. -3 -> 11
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