LeetCode-in-All
543. Diameter of Binary Tree
Easy
Given the root of a binary tree, return the length of the diameter of the tree.
The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not pass through the root.
The length of a path between two nodes is represented by the number of edges between them.
Example 1:
Input: root = [1,2,3,4,5]
Output: 3
Explanation: 3 is the length of the path [4,2,1,3] or [5,2,1,3].
Example 2:
Input: root = [1,2]
Output: 1
Constraints:
- The number of nodes in the tree is in the range
[1, 104]. -100 <= Node.val <= 100
Solution
import com_github_leetcode.TreeNode
/*
* Example:
* var ti = TreeNode(5)
* var v = ti.`val`
* Definition for a binary tree node.
* class TreeNode(var `val`: Int) {
* var left: TreeNode? = null
* var right: TreeNode? = null
* }
*/
class Solution {
private var diameter = 0
fun diameterOfBinaryTree(root: TreeNode?): Int {
diameter = 0
diameterOfBinaryTreeUtil(root)
return diameter
}
private fun diameterOfBinaryTreeUtil(root: TreeNode?): Int {
if (root == null) {
return 0
}
val leftLength = if (root.left != null) 1 + diameterOfBinaryTreeUtil(root.left) else 0
val rightLength = if (root.right != null) 1 + diameterOfBinaryTreeUtil(root.right) else 0
diameter = Math.max(diameter, leftLength + rightLength)
return Math.max(leftLength, rightLength)
}
}