内部排序

几种内部排序的实现

void SelectSort(int *a,int n)
{
	for (int i = 0; i < n - 1; i++)
	{
		int flag = -1;
		for (int j = i + 1; j < n; j++)
		{
			if (a[i] > a[j])
			{
				flag = j;
			}
		}
		if (flag != -1)
		{
			int temp = a[i];
			a[i] = a[flag];
			a[flag] = temp;
		}
	}
}
void InsertSort(int *a, int n)
{
	int j;
	for (int i = 1; i < n; i++)
	{
		int temp = a[i];
		for (j = i-1; j >= 0; j--)
		{

			if (temp<a[j])
			{
				a[j+1] = a[j];
			}
			else
			{
				break;
			}
		}
		a[j+1] = temp;
	}
}
void BubbleSort(int *a, int n)
{
	for (int i = 0; i < n - 1; i++)
	{
		for (int j = 0; j < n - i-1; j++)
		{
			if (a[j]>a[j + 1])
			{
				int temp = a[j];
				a[j] = a[j + 1];
				a[j + 1] = temp;
			}

		}
	}
}
void DoubleBubbleSort(int *a, int n)
{
	int t = 0;
	int s = n;
	while (t < n / 2&&s>n/2)
	{
		for (int i = t; i < s-1; i++)
		{
			if (a[i]>a[i + 1])
			{
				int temp = a[i];
				a[i] = a[i + 1];
				a[i + 1] = temp;
			}
		}
		s--;
		for (int j = s; j > t; j--)
		{
			if (a[j] < a[j - 1])
			{
				int temp = a[j];
				a[j] = a[j - 1];
				a[j - 1] = temp;
			}
		}
		t++;
	}
}
void Merge(int *a, int begin, int mid, int end)
{
	int n1 = 0;
	int n2 = 0;
	n1 = mid - begin + 1;
	n2 = end - mid;
	int *before = new int[n1];
	int *after = new int[n2];
	int i = 0;
	int j = 0;
	int k = begin;
	for (i = 0; i < n1; i++)
	{
		before[i] = a[k];
		k++;
	}
	for (j = 0; j < n2; j++)
	{
		after[j] = a[k];
		k++;
	}
	i = 0;
	j = 0;
	for (k = begin;i<n1&&j<n2; k++)
	{
		if (before[i]>after[j])
		{
             a[k] = after[j];
			 j++;
		}
		else
		{
			a[k] = before[i];
			i++;
		}
	}
	if (i < n1)
		while (i < n1)
		{
		a[k] = before[i];
		i++;
		k++;
		}
	else
		while (j < n2)
		{
		a[k] = after[j];
		j++;
		k++;
		}
}
void MergeSort(int *a, int begin, int end)
{
	if (begin < end)
	{
		int mid = (begin + end) / 2;
		MergeSort(a, begin, mid);
		MergeSort(a, mid + 1, end);
		Merge(a, begin, mid, end);
	}
}
void QuickSort(int *a, int left,int right)
{
	if (left > right)
		return;
	int x = a[left];
	int i = left;
	int j = right;
	while (i < j)
	{
		while (i<j&&a[j] > x)
			j--;
		if (i < j)
			a[i++] = a[j];
		while (i<j&&a[i] < x)
			i++;
		if (i < j)
			a[j--] = a[i];
	}
	a[i] = x;
	QuickSort(a,left,i-1);
	QuickSort(a,i+1, right);
}
void ShellSort(int *a, int n)
{
	for (int h = n / 2; h > 0; h /= 2)
	{
		for (int i = h; i < n; i++)
		{
			int temp = a[i];
			int j;
			for (j = i - h; j >= 0; j -= h)
			{
				if (a[j]>a[i])
					a[j + h] = a[j];
				else
					break;
			}
			a[j + h] = temp;
		}
	}
}
void Heapfy(int A[], int idx, int max)      //建立最大堆
{
	int left = idx * 2 + 1;
	int right = left + 1;

	int largest = idx;

	if (left<max&&A[left]>A[idx]){ largest = left; }

	if (right<max&&A[largest]<A[right]){ largest = right; }

	if (largest != idx)
	{
		int temp = A[largest];
		A[largest] = A[idx];
		A[idx] = temp;
		Heapfy(A, largest, max);

	}
}

void HeapSort(int A[], int ll)
{
	int len = ll;
	for (int i = len / 2 - 1; i >= 0; --i)
	{
		Heapfy(A, i, len);
	}
	for (int i = len - 1; i >= 1; --i)
	{
		int temp = A[0];
		A[0] = A[i];
		A[i] = temp;
		Heapfy(A, 0, i);
	}
}
int main()
{
	int a[] = { 3, 2, 5, 1, 3, 7, 6, 8 };
	int n = sizeof(a) / sizeof(a[0]);
	//DoubleBubbleSort(a, n);
	//MergeSort(a, 0, n-1);
	//QuickSort(a, 0, n - 1);
	//ShellSort(a, n);
	HeapSort(a, n);
	for (int i = 0; i < n; i++)
	{
		cout << a[i] << '\t';
	}
	getchar();
}

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