236. 二叉树的最近公共祖先 (Swift版本)

依旧风轻2024-03-11 15:20

题目

给定一个二叉树, 找到该树中两个指定节点的最近公共祖先。

数据结构

swift 复制代码

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public var val: Int
 *     public var left: TreeNode?
 *     public var right: TreeNode?
 *     public init(_ val: Int) {
 *         self.val = val
 *         self.left = nil
 *         self.right = nil
 *     }
 * }
 */

树中节点数目在范围 $2, 105$ 内。
-109 <= Node.val <= 109
所有 Node.val 互不相同。
p != q
p 和 q 均存在于给定的二叉树中。

Show me the code

swift 复制代码

    func lowestCommonAncestor(_ root: TreeNode?, _ p: TreeNode?, _ q: TreeNode?) -> TreeNode? {
        var result: TreeNode? = nil
        func containAnyTarget(_ root: TreeNode?, _ p: TreeNode?, _ q: TreeNode?) -> Bool {
            guard root != nil else { return false }
            let lson = containAnyTarget(root!.left, p, q)
            let rson = containAnyTarget(root!.right, p, q)
            if lson == true, rson == true {
                result = root
                return true
            }
            if root === p || root === q { 
                result = root
                return true
            }
            return lson || rson
        }
        let _ = containAnyTarget(root, p, q)
        return result
    }