Watch 10 video solutions for Number of Good Leaf Nodes Pairs, a medium level problem involving Tree, Depth-First Search, Binary Tree. This walkthrough by Fraz has 12,760 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
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:
Input: root = [1,2,3,null,4], distance = 3 Output: 1 Explanation: The leaf nodes of the tree are 3 and 4 and the length of the shortest path between them is 3. This is the only good pair.
Example 2:
Input: root = [1,2,3,4,5,6,7], distance = 3 Output: 2 Explanation: The good pairs are [4,5] and [6,7] with shortest path = 2. The pair [4,6] is not good because the length of ther shortest path between them is 4.
Example 3:
Input: root = [7,1,4,6,null,5,3,null,null,null,null,null,2], distance = 3 Output: 1 Explanation: The only good pair is [2,5].
Constraints:
tree is in the range [1, 210].1 <= Node.val <= 1001 <= distance <= 10