It's nicely balanced between the algorithmic/mathematical side and actual implementation. Most of the examples are simple enough that they can be written in a procedural language like C in a very short amount of time.
// get a combination of a rank
// n number k choices N rank
void unrankComb(int* &K, int n, int k, int N)
{
int e, N2, t, m, p;
e = nCr(n,k);
N2 = e-1-N;
e = ((n - k)*e)/n;
t = n - k + 1;
m = k;
p = n -1;
do
{
if(e <= N2)
{
K[k-m] = n - t - m + 2;
if(e > 0)
{
N2 = N2 -e;
e = (e * m) / p;
}
m = m -1;
p = p -1;
}
else
{
e = ((p - m)*e) / p;
t = t - 1;
p = p - 1;
}
}while(m != 0);
}
Do you need something like this:
// get a combination of a rank
// n number k choices N rank
void unrankComb(int* &K, int n, int k, int N)
{
int e, N2, t, m, p;
e = nCr(n,k);
N2 = e-1-N;
e = ((n - k)*e)/n;
t = n - k + 1;
m = k;
p = n -1;
do
{
if(e <= N2)
{
K[k-m] = n - t - m + 2;
if(e > 0)
{
N2 = N2 -e;
e = (e * m) / p;
}
m = m -1;
p = p -1;
}
else
{
e = ((p - m)*e) / p;
t = t - 1;
p = p - 1;
}
}while(m != 0);
}
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这并不是你问题的答案，但是有一本关于这个主题的优秀书籍，名为 组合算法：生成、枚举和搜索。
它在算法/数学方面和实际实现之间取得了很好的平衡。大多数示例都很简单，可以在很短的时间内用 C 等过程语言编写。
It's not quite an answer to your question, but there is an excellent book on exactly this topic called Combinatorial Algorithms: Generation, Enumeration, and Search.
It's nicely balanced between the algorithmic/mathematical side and actual implementation. Most of the examples are simple enough that they can be written in a procedural language like C in a very short amount of time.
你需要这样的东西吗：
Do you need something like this: