BinarySearch & LinearSearch

SearchManager.playground

import UIKit
import XCPlayground
import Foundation

func makeArr(n: Int) -> [Int] {
    var res = [Int]()
    for _ in 0..<n {
        res.append(Int(arc4random_uniform(10000) + 1))
    }
    
    return res
}

var arr = makeArr(n: 32)
arr.sort()

// Linear Search
var linearSearchSteps = 0

func linearSearch(_ array: [Int], key: Int) -> Int? {
    
    for (index, element) in array.enumerated() {
        linearSearchSteps = linearSearchSteps + 1
        
        if element == key {
            return index
        }
    }
    
    return nil

}


// Binary Search
var binarysearchSteps = 0

func binarySearch<T: Comparable>(_ array: [T], key: T, range: Range<Int>) -> Int? {
    
    if range.lowerBound >= range.upperBound {
        // search key is not in the array
        return nil
    } else {
        // split array at midpoint
        let midIndex = range.lowerBound + (range.upperBound - range.lowerBound) / 2
        binarysearchSteps = binarysearchSteps + 1
        
        // Check left half?
        if array[midIndex] > key {
            return binarySearch(array, key: key, range: range.lowerBound ..< midIndex)
        } else if array[midIndex] < key {   // Check Right half?
            return binarySearch(array, key: key, range: midIndex + 1 ..< range.upperBound)
        } else { // We have found the item
            return midIndex
        }
    }
}

// Pick out a random index
let randomIndex = Int(arc4random_uniform(UInt32(arr.count) - 1))
let randomNo = arr[randomIndex]

// Perform linear search
let linearFoundIndex = linearSearch(arr, key: randomNo)

// Perform binary search
let binaryFoundIndex = binarySearch(arr, key: randomNo, range: 0 ..< arr.count)