二叉树

TreeNode-class-define.swift

/// 二叉树节点
public class TreeNode {
    public var val: Int
    public var left: TreeNode?
    public var right: TreeNode?
    public init() { self.val = 0; self.left = nil; self.right = nil; }
    public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; }
    public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
        self.val = val
        self.left = left
        self.right = right
    }
    
    class func makeTree(_ array:[Int?]) -> TreeNode? {
        
        let count = array.count
        func plant(_ index:Int) -> TreeNode? {
            guard index < count, let value = array[index] else {
                return nil
            }
            let node = TreeNode.init(value)
            node.left = plant(index*2+1)
            node.right = plant(index*2+2)
            return node
        }
        return plant(0)
    }
}