选择排序、冒泡排序、插入如排序、归并排序、C++代码

选择排序

void selectsort(vector<int>&arr)
{
    
    
	if (arr.size() < 2) return;
	for (int i = 0; i < arr.size() - 1; i++)
	{
    
    
		int MIN = i;
		for (int j = i + 1; j < arr.size(); j++)
		{
    
    
			MIN = arr[MIN] < arr[j] ? MIN : j;
		}
		swap(arr[MIN], arr[i]);
	}
}

冒泡排序

void BubbleSort(vector<int>&arr)//冒泡排序
{
    
    
	for (int j = arr.size() - 1; j >= 0; j--)
	{
    
    
		for (int i = 0; i < j; i++)
		{
    
    
			if (arr[i] > arr[i + 1])
			{
    
    
				swap(arr, i, i + 1);
			}
		}
	}
}

插入排序

void InsertionSort(vector<int>&arr)//插入排序
{
    
    
	if (arr.size() < 2) return;
	for (int i = 1; i < arr.size(); i++)
	{
    
    
		for (int j = i - 1; j >= 0 && arr[j] > arr[j + 1]; j--)
		{
    
    
			swap(arr, j, j+1);
		}
	}
}

归并排序

void  Merge(vector<int>&arr, int l, int mid, int r)
{
    
    
	vector<int>help(r - l + 1);
	int i = 0;
	int p1 = l;
	int p2 = mid + 1;
	while (p1 <= mid && p2 <= r)
	{
    
    
		help[i++] = arr[p1] < arr[p2] ? arr[p1++] : arr[p2++];
	}
	while (p1 <= mid)
	{
    
    
		help[i++] = arr[p1++];
	}
	while (p2 <= r)
	{
    
    
		help[i++] = arr[p2++];
	}
	for (int i = 0; i < help.size(); i++)
	{
    
    
		arr[l + i] = help[i];
	}
}
void MergeSort(vector<int>&arr, int l, int r)
{
    
    
	if (l == r) return;
	int mid = l + (r - l) / 2;
	MergeSort(arr, l, mid );
	MergeSort(arr, mid + 1, r);
	Merge(arr, l, mid, r);


}

测试

int main()
{
    
    
	vector<int>a = {
    
     1,4,2,3,5,7,2,7,5 }; 
	MergeSort(a,0,a.size()-1);
	for (int i = 0; i < a.size(); i++)
	{
    
    
		cout << a[i] << endl;
	}
}