在计算机科学与数学中，一个排序算法（英语：Sorting algorithm）是一种能将一串数据依照特定排序方式进行排列的一种算法,这里总结几个常用算法的写法,包括冒泡排序,快速排序,插入排序,选择排序.
冒泡排序
func bubbleSort<T: Comparable> (oArr: [T]) -> [T] {
var arr = oArr
for outerIndex in (1...arr.count - 1).reversed() {
for innerIndex in 0..<outerIndex {
if arr[innerIndex] > arr[innerIndex + 1] {
let temp = arr[innerIndex]
arr[innerIndex] = arr[innerIndex + 1]
arr[innerIndex + 1] = temp
}
}
}
return arr
}快速排序
extension Array {
var decompose : (head: Element, tail: [Element])? {
return (count > 0) ? (self[0], Array(self[1..<count])) : nil
}
}
func quickSort<T: Comparable> (oArr: [T]) -> [T] {
let arr = oArr
if let (pivot, rest) = arr.decompose {
let lesser = rest.filter { $0 < pivot }
let greater = rest.filter { $0 >= pivot }
let les = quickSort(oArr: lesser)
let gre = quickSort(oArr: greater)
return les + [pivot] + gre
} else {
return []
}
}插入排序
func insertionSort<T: Comparable> (oArr: [T]) -> [T] {
var arr = oArr
for outerIndex in 1..<arr.count {
let temp = arr[outerIndex]
var innerIndex = outerIndex
while innerIndex > 0 && arr[innerIndex - 1] >= temp {
arr[innerIndex] = arr[innerIndex - 1]
innerIndex -= 1
}
arr[innerIndex] = temp
}
return arr
}选择排序
func selectSort<T: Comparable> (oArr: [T]) -> [T] {
var arr = oArr
var minIndex = 0 // 记录每次遍历的最小值位置
for outerIndex in 0..<arr.count {
minIndex = outerIndex
for innerIndex in (outerIndex + 1)..<arr.count {
if arr[minIndex] > arr[innerIndex] {
minIndex = innerIndex // 判断最小值,记住下表
}
if minIndex != outerIndex {
let temp = arr[outerIndex]
arr[outerIndex] = arr[minIndex]
arr[minIndex] = temp
}
}
}
return arr
}更多的排序算法可以去wiki百科看看