算法导论C语言实现各算法代码集合-第二章

1：插入排序

#include 

void InsertionSort(int arr[], int length)
{
	for (int i = 1; i < length; i++)
	{
		int key = arr[i], j = i;
		for (j = i; j > 0; j--)
		{
			if (key < arr[j - 1])
			{
				arr[j] = arr[j - 1];
			}
			else
			{
				break;
			}
		}
		arr[j] = key;
	}
}
void Show(int arr[], int length)
{
	for (int i = 0; i < length; i++)
		printf("%d ", arr[i]);
	printf("\n");
}

int main()
{
	int arr[10] = {4, 2, 8, 1, 9, 6, 10, 3, 7, 5};
	Show(arr, 10);
	InsertionSort(arr, 10);
	Show(arr, 10);
	return 0;
}

2：归并排序（分治策略）（需占用额外空间）

#include 

void SubMerge(int arr[], int l, int r)
{
	if (l == r)
		return;

	int m = (l + r) / 2;
	SubMerge(arr, l, m);
	SubMerge(arr, m + 1, r);

	int t[10];
	int i = 0, j = 0, k = 0;
	for (i = l, j = m + 1; i <= m || j <= r; k++)
	{
		if (i > m)
		{
			t[k] = arr[j];
			j++;
			continue;
		}
		if (j > r)
		{
			t[k] = arr[i];
			i++;
			continue;
		}
		if (arr[i] < arr[j])
		{
			t[k] = arr[i];
			i++;
		}
		else
		{
			t[k] = arr[j];
			j++;
		}
	}
	for (int m = l; m <= r; m++)
	{
		arr[m] = t[m - l];
	}
}
void MergeSort(int arr[], int length)
{
	SubMerge(arr, 0, length - 1);
}
void Show(int arr[], int length)
{
	for (int i = 0; i < length; i++)
		printf("%d ", arr[i]);
	printf("\n");
}

int main()
{
	int arr[10] = {4, 2, 8, 1, 9, 6, 10, 3, 7, 5};
	Show(arr, 10);
	MergeSort(arr, 10);
	Show(arr, 10);
	return 0;
}