随机采样算法(从N个数中抽取M个数) C++

#include 
#include 
#include 
#include 
//假设这n个数的序号依次为0,1,2,...,n-1,数组名为num
void knuth1(std::vector<int> pNum, int m, int n)
{
	srand((unsigned int)time(0));
	for (int i = 0; i < n; i++)
	{
		if (rand() % (n - i) < m)//rand()%(n-i)的取值范围是[0, n-i）
		{
			std::cout << pNum[i] << std::endl;
			m--;
		}
	}
}
int main(int argc, char *argv[])
{
	std::vector<int> iv;
	generate_n(std::back_inserter(iv), 5, [] {return rand() % 10; });
	knuth1(iv,1,5);
	return 0;
}