几种排序算法C++实现

#include <iostream>
using namespace std;
//堆排序
void AdjustDown(int* arr, int parent, int size)
{
int maxChild = parent * 2 + 1;
while (maxChild < size)
{
if (maxChild + 1 < size && arr[maxChild] < arr[maxChild + 1])
maxChild++;
if (arr[parent] > arr[maxChild])
{
break;
}
else
{
std::swap(arr[parent], arr[maxChild]);
parent = maxChild;
maxChild = parent * 2 + 1;
}
}

}
void HeapSort(int* arr, int size)
{
//建大堆
int nonLeaf = (size - 2) / 2;
int n = size - 1;
for (; nonLeaf >= 0; nonLeaf--)
{
AdjustDown(arr, nonLeaf, size);
}
//第一个值与最后一个值交换
while (n > 0)
{
std::swap(arr[0], arr[n]);
AdjustDown(arr, 0, n);
n--;
}
}


//冒泡排序
void BubbleSort(int* arr, int size)
{
int end, index, last;
end =  size - 1;
while (end > 0)
{
last = 0; //记录最后一次被修改的位置
for (index = 0; index < end; index++)
{
if (arr[index] > arr[index + 1])
{
std::swap(arr[index], arr[index + 1]);
last = index;
}
}
end = last; //下次遍历到最后一次被修改的位置
}
}
//快速排序
int PartSort(int* arr, int left, int right)
{
int end = right - 1;
right = end - 1;
while (left < right)
{
while (left < right && arr[left] <= arr[end])
left++;
while (left < right && arr[right] > arr[end])
right--;
if (left < right)
std::swap(arr[left], arr[right]);
}
if (arr[left] > arr[end])
{
std::swap(arr[left], arr[end]);
return left;
}
else
{
//std::swap(arr[left + 1], arr[end]);
//return left + 1;
return end;
}
}
void QuickSort(int* arr, int size)
{
if (size > 1)
{
int mid = PartSort(arr, 0, size);
QuickSort(arr, mid);
if (mid < size-1)
QuickSort(&arr[mid + 1], size - mid - 1);
}
}
//选择排序
void SelectSort(int* arr, int size)
{
int left = 0;
int right = size - 1; //前后指针一次找出最大和最小值
int maxIndex, minIndex;
while (left < right)
{
minIndex = maxIndex = left;
for (int index = left; index <= right; index++)
{
if (arr[index] < arr[minIndex])
minIndex = index;
if (arr[index] > arr[maxIndex])
maxIndex = index;
}
std::swap(arr[left], arr[minIndex]);
if (maxIndex == left)
maxIndex = minIndex;
std::swap(arr[maxIndex], arr[right]);
left++;
right--;
}
}
int main()
{
int arr[] = { 2, 5, 4, 9, 3, 6, 8, 7, 0, 1, 0, 1, 5, 2, 7, 8, 9, 2, 3, 4 };
//HeapSort(arr, sizeof(arr) / sizeof(arr[0]));
//BubbleSort(arr, sizeof(arr) / sizeof(arr[0]));
//QuickSort(arr, sizeof(arr) / sizeof(arr[0]));
SelectSort(arr, sizeof(arr) / sizeof(arr[0]));
for (int i = 0; i < sizeof(arr) / sizeof(arr[0]); i++)
{
cout << arr[i] << ' ';
}
cout << endl;
return 0;
}