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865 Smallest Subtree with all the Deepest Nodes.swift
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865 Smallest Subtree with all the Deepest Nodes.swift
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//
// 865 Smallest Subtree with all the Deepest Nodes.swift
// LeetCode-Solutions
//
// Created by Aleksandar Dinic on 12/12/2020.
// Copyright © 2020 Aleksandar Dinic. All rights reserved.
//
import Foundation
/// Source: https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes/
class Solution {
/// Finds the smallest subtree such that it contains all the deepest nodes in
/// the original tree.
///
/// - Parameter root: Binary tree root.
/// - Returns: The smallest subtree.
///
/// - Complexity:
/// - time: O(n), where n is the number of nodes in the tree.
/// - space: O(n), where n is the number of nodes in the tree.
func subtreeWithAllDeepest(_ root: TreeNode?) -> TreeNode? {
dfs(root).node
}
private func dfs(_ root: TreeNode?) -> (node: TreeNode?, dist: Int) {
guard let root = root else { return (nil, 0) }
let left = dfs(root.left)
let right = dfs(root.right)
if left.dist > right.dist {
return (left.node, left.dist + 1)
}
if left.dist < right.dist {
return (right.node, right.dist + 1)
}
return (root, left.dist + 1)
}
}
/// Provided code
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
}
}