剑指 Offer II 052. 展平二叉搜索树

func increasingBST(_ root: TreeNode?) -> TreeNode? {
    
        var array = Array<Int>()
        dealTree(root, &array)
        var node : TreeNode?
        var tempNode : TreeNode?

        for i in 0..<array.count  {
            
            if node == nil {
                node = TreeNode(array[i])
                tempNode = node
            }else {
                
                let node1 = TreeNode(array[i])
                node?.right = node1
                node = node1
            }
            
        }
        
        return tempNode
        
    }
    
    func dealTree(_ root:TreeNode? ,_ array:inout Array<Int>) {
        
        if root == nil {
            return
        }
        
        dealTree(root?.left,&array)
        array.append((root?.val)!)
        dealTree(root?.right,&array)
        
    }