Number of Good Leaf Nodes Pairs
You are given the root of a binary tree and an integer distance. A pair of two different leaf nodes of a binary tree is said to be good if the length of the shortest path between them is less than or equal to distance.
Return the number of good leaf node pairs in the tree.
Example 1
1
/ \
2 3
\
4Input
root = [1,2,3,null,4], distance = 3Output
1The leaf nodes of the tree are 3 and 4 and the length of the shortest path between them is 3, so this is the only good pair.
Example 2
1
/ \
2 3
/ \ / \
4 5 6 7Input
root = [1,2,3,4,5,6,7], distance = 3Output
2The good pairs are [4,5] and [6,7] with shortest path = 2, while [4,6] is not good because the length of their shortest path is 4.
Constraints
- The number of nodes in the
treeis in the range[1, 2^10]. 1 <= Node.val <= 1001 <= distance <= 10