Cousins in Binary Tree

Cousins.swift

func isCousins(_ root: TreeNode?, _ x: Int, _ y: Int) -> Bool {
        var queue: [(node: TreeNode, depth: Int, parentVal: Int)] = [(root!, 0, -1)]
        var xd: (depth: Int?, parentVal: Int) = (nil, -1), yd: (depth: Int?, parentVal: Int) = (nil, -1)
        while queue.count > 0 {
            let (node, depth, parentVal) = queue.removeLast()
            if node.val == x { xd = (depth, parentVal) }
            if node.val == y { yd = (depth, parentVal) }
            if xd.depth != nil && yd.depth != nil { return xd.depth == yd.depth && xd.parentVal != yd.parentVal }
            if node.left != nil { queue.append((node.left!, depth + 1, node.val)) }
            if node.right != nil { queue.append((node.right!, depth + 1, node.val)) }
        }
        return false
    }