1.冒泡排序
算法描述
- 比较相邻的元素。如果第一个比第二个大，就交换它们两个；
- 对每一对相邻元素作同样的工作，从开始第一对到结尾的最后一
对，这样在最后的元素应该会是最大的数； - 针对所有的元素重复以上的步骤
func sortBybub() {
var arr = [0,8,7,9,6,5,3,4,9,1,2,8]
for i in 0..<arr.count-1 {
var j = 1;
while j<arr.count-i {
if arr[j]<arr[j-1] {
let tem = arr[j];
arr[j] = arr[j-1]
arr[j-1] = tem;
}
j+=1;
}
}
}
2.选择排序
算法描述
- n个记录的直接选择排序可经过n-1趟直接选择排序得到有序结果。具体算法描述如下：
- 初始状态：无序区为R[1..n]，有序区为空；
- 第i趟排序(i=1,2,3…n-1)开始时，当前有序区和无序区分别为R[1..i-1]和R(i..n）。该趟排序从当前无序区中-选出关键字最小的记录 R[k]，将它与无序区的第1个记录R交换，使R[1..i]和R[i+1..n)分别变为记录个数增加1个的新有序区和记录个数减少1个的新无序区；
n-1趟结束，数组有序化了。
func sortBychoice() {
var arr = [1,2,88,65,76,43,45,32,34,37,68,65,49,67,20,35,38];
for i in 0..<arr.count-1 {
var index = i
for j in i+1..<arr.count {
if arr[j]<arr[index] {
index = j
}
}
if index != i {
let tem = arr[index]
arr[index] = arr[i];
arr[i] = tem;
}
}
print("choice==\(arr)")
}
3.插入排序
func sortByinsert() {
var arr = [4,2,3,6,5,7,1,9,8]
for i in 0..<arr.count-1 {
var j=i+1;
while j > 0 {
if arr[j]<arr[j-1] {
let tem = arr[j];
arr[j] = arr[j-1]
arr[j-1] = tem;
j-=1;
}else{
break;
}
}
}
print("arrsss===\(arr)");
}
4 希尔排序
func sortByxe() {
var arr = [1,2,88,65,76,43,45,32,34,37,68,65,49,67,20,35,38];
var step = arr.count/2
while step>0 {
for i in 0..<arr.count {
var j = i+step;
while j>=step&&j<arr.count {
if arr[j-step]>arr[j] {
let tem = arr[j-step]
arr[j-step] = arr[j]
arr[j] = tem;
j=j-step;
}else{
break
}
}
}
step = step/2;
}
print("xr ==\(arr)")
}
5.归并排序
func sortBycombine(){
var arr = [1,2,88,65,76,43,45,32,34,37,68,65,49,67,20,35,38];
let result = mergeSort(array: arr)
print("result\(result)")
}
//快速排序
func mergeSort(array:[Int])->[Int]{
if array.count<2 {
return array
}
let middle = array.count/2
print("data==\(array)")
let left = mergeSort(array: Array(array[0..<middle]))
let right = mergeSort(array: Array(array[middle..<array.count]))
return merge(left: left, right: right)
}
func merge(left:[Int],right:[Int]) -> [Int] {
var leftindex = 0
var right_index = 0
var combin_arr = [Int]()
while leftindex<left.count&&right_index<right.count {
if left[leftindex]>right[right_index] {
combin_arr.append(right[right_index])
right_index+=1
}else{
combin_arr.append(left[leftindex])
leftindex+=1
}
}
while leftindex<left.count {
combin_arr.append(left[leftindex])
leftindex+=1
}
while right_index<right.count {
combin_arr.append(right[right_index])
right_index+=1
}
return combin_arr
}
6.快速排序
func sortByquick() {
var arr = [1,2,88,65,76,43,45,32,34,37,68,65,49,67,20,35,38];
quickSort(arr: &arr, low: 0, high: arr.count-1)
}
func quickSort(arr:inout [Int],low:Int,high:Int) {
if low>high {
return;
}
let index = findIndex(arr: &arr, low: low, high: high)
quickSort(arr: &arr, low: low, high: index-1)
quickSort(arr: &arr, low: index+1, high: high)
}
//不稳定排序
func findIndex(arr:inout [Int],low:Int,high:Int)->Int{
let num = arr[high]
var currentIndex = low
for index in low...high {
if arr[index]<num {
if currentIndex != index {
arr.swapAt(currentIndex, index)
}
currentIndex+=1//currentIndex 前都是小于num的值 最后交换high和currentIndex,即可实现currentIndex前都是小于num的，后都是大于的
}
}
if currentIndex != high {
arr.swapAt(currentIndex, high)
}
return currentIndex;
}
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