LeetCode/kt/lowest-common-ancestor-of-deepest-leaves.kt

class Solution {
    private fun dfs(node: TreeNode?): Pair<TreeNode?, Int> =
        when {
            node == null -> null to 0
            else -> {
                val (left, leftDepth) = dfs(node.left)
                val (right, rightDepth) = dfs(node.right)

                when {
                    leftDepth < rightDepth -> right to rightDepth + 1
                    leftDepth > rightDepth -> left to leftDepth + 1
                    else -> node to leftDepth + 1
                }
            }
        }

    fun lcaDeepestLeaves(root: TreeNode?): TreeNode? = dfs(root).let { (node, _) -> node }
}