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Implemented 'Closest Nodes Queries in a Binary Search Tree' challenge
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96 changes: 96 additions & 0 deletions
96
LeetCode/LeetCode/Challenges/ClosestNodesQueriesInABinarySearchTree.swift
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,96 @@ | ||
| // | ||
| // ClosestNodesQueriesInABinarySearchTree.swift | ||
| // LeetCode | ||
| // | ||
| // Created by William Boles on 23/02/2024. | ||
| // | ||
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| import Foundation | ||
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| //https://leetcode.com/problems/closest-nodes-queries-in-a-binary-search-tree/ | ||
| struct ClosestNodesQueriesInABinarySearchTree { | ||
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| //Time: O( | ||
| //Space: O( | ||
| //binary tree | ||
| //binary search tree | ||
| //binary search | ||
| //in-order | ||
| //DFS | ||
| //recursive | ||
| //inout | ||
| //array | ||
| // | ||
| //Solution Description: | ||
| //As this is binary search tree, we know that an in-order traversal will produce a sorted array. With a sorted array we can | ||
| //then perform two binary searches to find both the upper and lower bounds of each query item. | ||
| func closestNodes(_ root: TreeNode?, _ queries: [Int]) -> [[Int]] { | ||
| guard let root = root else { | ||
| return [[Int]]() | ||
| } | ||
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| var values = [Int]() | ||
| inorder(root, &values) | ||
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| var result = [[Int]]() | ||
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| for query in queries { | ||
| let min = findMax(values, query) | ||
| let max = findMin(values, query) | ||
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| result.append([min, max]) | ||
| } | ||
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| return result | ||
| } | ||
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| private func inorder(_ root: TreeNode?, _ order: inout [Int]) { | ||
| guard let root = root else { | ||
| return | ||
| } | ||
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| inorder(root.left, &order) | ||
| order.append(root.val) | ||
| inorder(root.right, &order) | ||
| } | ||
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| private func findMax(_ values: [Int], _ target: Int) -> Int { | ||
| var left = 0 | ||
| var right = values.count - 1 | ||
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| var result = -1 | ||
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| while left <= right { | ||
| let mid = left + (right - left) / 2 //to avoid overflow | ||
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| if values[mid] <= target { //find the upper bounds that is less than or equal to target | ||
| result = values[mid] //we know that values[mid] is a valid result so store it and check again | ||
| left = mid + 1 | ||
| } else { | ||
| right = mid - 1 | ||
| } | ||
| } | ||
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| return result | ||
| } | ||
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| private func findMin(_ values: [Int], _ target: Int) -> Int { | ||
| var left = 0 | ||
| var right = values.count - 1 | ||
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| var result = -1 | ||
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| while left <= right { | ||
| let mid = left + (right - left) / 2 //to avoid overflow | ||
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| if values[mid] >= target { //find the lower bounds that is greater than or equal to target | ||
| result = values[mid] //we know that values[mid] is a valid result so store it anad check again | ||
| right = mid - 1 | ||
| } else { | ||
| left = mid + 1 | ||
| } | ||
| } | ||
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| return result | ||
| } | ||
| } |
70 changes: 70 additions & 0 deletions
70
LeetCode/LeetCodeTests/Tests/ClosestNodesQueriesInABinarySearchTreeTests.swift
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,70 @@ | ||
| // | ||
| // ClosestNodesQueriesInABinarySearchTreeTests.swift | ||
| // LeetCodeTests | ||
| // | ||
| // Created by William Boles on 23/02/2024. | ||
| // | ||
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| import XCTest | ||
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| @testable import LeetCode | ||
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| final class ClosestNodesQueriesInABinarySearchTreeTests: XCTestCase { | ||
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| //MARK: - Tests | ||
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| func test_A() { | ||
| let data = [6,2,13,1,4,9,15,nil,nil,nil,nil,nil,nil,14] | ||
| let queries = [2,5,16] | ||
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| let root = TreeNode.deserialize(data) | ||
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| let result = ClosestNodesQueriesInABinarySearchTree().closestNodes(root, queries) | ||
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| XCTAssertEqual(result, [[2,2],[4,6],[15,-1]]) | ||
| } | ||
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| func test_B() { | ||
| let data = [4,nil,9] | ||
| let queries = [3] | ||
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| let root = TreeNode.deserialize(data) | ||
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| let result = ClosestNodesQueriesInABinarySearchTree().closestNodes(root, queries) | ||
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| XCTAssertEqual(result, [[-1,4]]) | ||
| } | ||
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| func test_C() { | ||
| let data = [16,8,18,1,12,nil,20,nil,2,9,nil,nil,nil,nil,7] | ||
| let queries = [8,14,285508,6] | ||
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| let root = TreeNode.deserialize(data) | ||
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| let result = ClosestNodesQueriesInABinarySearchTree().closestNodes(root, queries) | ||
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| XCTAssertEqual(result, [[8,8],[12,16],[20,-1],[2,7]]) | ||
| } | ||
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| func test_D() { | ||
| let data = [16,14,nil,4,15,1] | ||
| let queries = [10,6,2,9] | ||
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| let root = TreeNode.deserialize(data) | ||
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| let result = ClosestNodesQueriesInABinarySearchTree().closestNodes(root, queries) | ||
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| XCTAssertEqual(result, [[4,14],[4,14],[1,4],[4,14]]) | ||
| } | ||
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| func test_E() { | ||
| let data = [9,6,14,nil,nil,13,20,12] | ||
| let queries = [19,10,9,17,19,6,10,19,13,6] | ||
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| let root = TreeNode.deserialize(data) | ||
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| let result = ClosestNodesQueriesInABinarySearchTree().closestNodes(root, queries) | ||
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| XCTAssertEqual(result, [[14,20],[9,12],[9,9],[14,20],[14,20],[6,6],[9,12],[14,20],[13,13],[6,6]]) | ||
| } | ||
| } |