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270 Closest Binary Search Tree Value.swift
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270 Closest Binary Search Tree Value.swift
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//
// 270 Closest Binary Search Tree Value.swift
// LeetCode-Solutions
//
// Created by Aleksandar Dinic on 08/08/2020.
// Copyright 漏 2020 Aleksandar Dinic. All rights reserved.
//
import Foundation
/// Source: https://leetcode.com/problems/closest-binary-search-tree-value/
class Solution {
/// Finds the value in the BST that is closest to the target.
///
/// - Parameters:
/// - root: Binary search tree root.
/// - target: The target.
/// - Returns: The value that is closest to the target.
///
/// - Complexity:
/// - time: O(h), where h is the height of the binary search tree.
/// - space: O(1), only constant space is used.
func closestValue(_ root: TreeNode?, _ target: Double) -> Int {
guard let root = root else { return -1 }
var curr: TreeNode? = root
var closest = root.val
var val = Int.max
while curr != nil {
val = curr?.val ?? Int.max
closest = abs(Double(val) - target) < abs(Double(closest) - target) ? val : closest
curr = target < Double(val) ? curr?.left : curr?.right
}
return closest
}
}
/// 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
}
}