Created
February 19, 2019 15:38
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BinarySearch
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import Foundation | |
// Binary search using simple function | |
func binSearch (list: [Int], value: Int) -> Int?{ | |
if !list.isEmpty{ | |
var indexMin = list.startIndex | |
var indexMax = list.endIndex-1 | |
while indexMin <= indexMax{ | |
let indexMid = indexMin + (indexMax - indexMin)/2 | |
if list[indexMid] == value{ | |
return indexMid | |
} | |
if value < list[indexMid]{ | |
indexMax = indexMid-1 | |
} | |
else{ | |
indexMin = indexMid+1 | |
} | |
} | |
} | |
return nil | |
} | |
// Binary search using recursive function | |
func binarySearchRecursion(element: Int, in array: [Int]) -> Int? { | |
var startIndex = 0 | |
var endIndex = array.count - 1 | |
let middle = Int((startIndex + endIndex) / 2) | |
if !array.isEmpty { | |
if array[middle] == element { | |
return element | |
} else if array.count == 1 { | |
return nil | |
} | |
if array[middle] < element { | |
startIndex = middle + 1 | |
} else if array[middle] > element { | |
endIndex = middle - 1 | |
} | |
let subArray = Array(array[startIndex...endIndex]) | |
return binarySearchRecursion(element: element, in: subArray) | |
} else { | |
return nil | |
} | |
} | |
// Helper method to get elapsed time | |
func printTimeElapsedWhenRunningCode(title: String, operation:()->()) { | |
let startTime = CFAbsoluteTimeGetCurrent() | |
operation() | |
let timeElapsed = (CFAbsoluteTimeGetCurrent() - startTime) * 1000 | |
let value = String(format: "%.2f ms.", timeElapsed) | |
print("Time elapsed for \(title): \(value)") | |
} | |
let array100Elements = Array(0...99) | |
let array10000Elements = Array(0...9_999) | |
let a = 51 | |
let b = 5001 | |
printTimeElapsedWhenRunningCode(title: "Simple loop search with \(array100Elements.count) elements") { | |
for item in array100Elements { | |
if item == a { | |
break | |
} | |
} | |
} | |
printTimeElapsedWhenRunningCode(title: "Simple loop search with \(array10000Elements.count) elements") { | |
for item in array10000Elements { | |
if item == b { | |
break | |
} | |
} | |
} | |
print(" \n*********************************\n ") | |
printTimeElapsedWhenRunningCode(title: "Functional search with \(array100Elements.count) elements") { | |
_ = array100Elements.filter({ $0 == a }) | |
} | |
printTimeElapsedWhenRunningCode(title: "Functional search with \(array10000Elements.count) elements") { | |
_ = array10000Elements.filter({ $0 == b }) | |
} | |
print(" \n*********************************\n ") | |
printTimeElapsedWhenRunningCode(title: "BinarySearch (simple) with \(array100Elements.count) elements") { | |
_ = binSearch(list: array100Elements, value: a) | |
} | |
printTimeElapsedWhenRunningCode(title: "BinarySearch (simple) with \(array10000Elements.count) elements") { | |
_ = binSearch(list: array10000Elements, value: b) | |
} | |
print(" \n*********************************\n ") | |
printTimeElapsedWhenRunningCode(title: "BinarySearch (recursive) with \(array100Elements.count) elements") { | |
_ = binarySearchRecursion(element: a, in: array100Elements) | |
} | |
printTimeElapsedWhenRunningCode(title: "BinarySearch (recursive) with \(array10000Elements.count) elements") { | |
_ = binarySearchRecursion(element: b, in: array10000Elements) | |
} |
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