DiameterOfBinaryTree543.kt

package 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
 */
// Problem #543
// https://leetcode.com/problems/diameter-of-binary-tree/

fun diameterOfBinaryTree(root: TreeNode?): Int {
    if(root == null)
        return 0
    val current = getMaxLength(root.left) + getMaxLength(root.right)
    val left = diameterOfBinaryTree(root.left)
    val right = diameterOfBinaryTree(root.right)
    return Math.max(current,Math.max(left,right))

}
private fun getMaxLength(root: TreeNode?):Int{
    if(root == null)
        return 0
    return 1+ Math.max(getMaxLength(root.left),getMaxLength(root.right))
}