常见排序整理

#include <stdio.h>
void BubbleSort(int arr[], int length);
int main()
{
	printf("*******排序算法*******\n") ;
	while(1)
	{
		printf("输入数字：") ;
		int i,n=0,a[n];
		for(i=0;; i++)
		{
			scanf("%d",&a[i]);
			n++;                      //计算输入个数
			if(getchar()=='\n')break; //遇回车中断
		}
		BubbleSort(a,n);
		for(i=0; i<n; i++)
		{
			if(i==n-1)
				printf("%d\n",a[i]);
			else if(i==0)
				printf("排序后：%d ",a[i]);
			else
				printf("%d ",a[i]);
		}
	}
}
//1 冒泡排序
void BubbleSort(int arr[], int length)
{
	for (int i = 0; i < length; i++)
	{
		for (int j = 0; j < length - i - 1; j++)
		{
			if (arr[j] > arr[j + 1])
			{
				int temp;
				temp = arr[j + 1];
				arr[j + 1] = arr[j];
				arr[j] = temp;
			}
		}
	}
}
//2 选择排序
void SelectionSort(int arr[], int length)
{
	for (int i = 0; i < length; i++)
	{
		int index = i;
		for (int j = i+1; j < length; j++)
		{
			if (arr[j] < arr[index])
			{
				index = j;
			}
		}
		if (index == i)
			continue;
		else
		{
			int temp;
			temp = arr[index];
			arr[index] = arr[i];
			arr[i] = temp;
		}
	}
}
//3 插入排序
void InsertSort(int arr[], int length)
{
	for (int i = 1; i < length; i++)
	{
		int j;
		if (arr[i] < arr[i - 1])
		{
			int temp = arr[i];
			for (j = i - 1; j >= 0 && temp < arr[j]; j--)
			{
				arr[j + 1] = arr[j];
			}
			arr[j + 1] = temp;
		}
	}
}
//4 希尔排序
void ShellSort(int arr[], int length)
{
	int increasement = length;
	int i, j, k;
	do
	{
		// 确定分组的增量
		increasement = increasement / 3 + 1;
		for (i = 0; i < increasement; i++)
		{
			for (j = i + increasement; j < length; j += increasement)
			{
				if (arr[j] < arr[j - increasement])
				{
					int temp = arr[j];
					for (k = j - increasement; k >= 0 && temp < arr[k]; k -= increasement)
					{
						arr[k + increasement] = arr[k];
					}
					arr[k + increasement] = temp;
				}
			}
		}
	}
	while (increasement > 1);
}
//5 快速排序
void QuickSort(int arr[], int start, int end)
{
	if (start >= end)
		return;
	int i = start;
	int j = end;
	// 基准数
	int baseval = arr[start];
	while (i < j)
	{
		// 从右向左找比基准数小的数
		while (i < j && arr[j] >= baseval)
		{
			j--;
		}
		if (i < j)
		{
			arr[i] = arr[j];
			i++;
		}
		// 从左向右找比基准数大的数
		while (i < j && arr[i] < baseval)
		{
			i++;
		}
		if (i < j)
		{
			arr[j] = arr[i];
			j--;
		}
	}
	// 把基准数放到i的位置
	arr[i] = baseval;
	// 递归
	QuickSort(arr, start, i - 1);
	QuickSort(arr, i + 1, end);
}
//6 归并排序
void MergeSort(int arr[], int start, int end, int * temp)
{
	if (start >= end)
		return;
	int mid = (start + end) / 2;
	MergeSort(arr, start, mid, temp);
	MergeSort(arr, mid + 1, end, temp);

	// 合并两个有序序列
	int length = 0; // 表示辅助空间有多少个元素
	int i_start = start;
	int i_end = mid;
	int j_start = mid + 1;
	int j_end = end;
	while (i_start <= i_end && j_start <= j_end)
	{
		if (arr[i_start] < arr[j_start])
		{
			temp[length] = arr[i_start];
			length++;
			i_start++;
		}
		else
		{
			temp[length] = arr[j_start];
			length++;
			j_start++;
		}
	}
	while (i_start <= i_end)
	{
		temp[length] = arr[i_start];
		i_start++;
		length++;
	}
	while (j_start <= j_end)
	{
		temp[length] = arr[j_start];
		length++;
		j_start++;
	}
	// 把辅助空间的数据放到原空间
	for (int i = 0; i < length; i++)
	{
		arr[start + i] = temp[i];
	}
}