/* the Euler algorithm */
public void shuffle1(char[] s, int l, int k)
{
int i, n_lets;
s_ = s;
l_ = l;
k_ = k;
if (k_ >= l_ || k_ <= 1) /* two special cases */
{
return;
}
/* use hashtable to find distinct vertices */
n_lets = l_ - k_ + 2; /* number of (k-1)-lets */
n_vertices = 0;
hinit(n_lets);
for (i = 0; i < n_lets; i++)
{
hinsert(i);
}
root = entries[n_lets - 1].i_vertices; /* the last let */
vertices = new vertex[n_vertices];
for (i = 0; i < n_vertices; i++)
{
vertices[i] = new vertex();
}
/* set i_sequence and n_indices for each vertex */
for (i = 0; i < n_lets; i++)
{ /* for each let */
hentry ev = entries[i];
vertex v = vertices[ev.i_vertices];
v.i_sequence = ev.i_sequence;
if (i < n_lets - 1) /* not the last let */
{
v.n_indices++;
}
}
/* allocate indices for each vertex */
for (i = 0; i < n_vertices; i++)
{ /* for each vertex */
vertex v = vertices[i];
v.indices = new int[v.n_indices];
}
/* populate indices for each vertex */
for (i = 0; i < n_lets - 1; i++)
{ /* for each edge */
hentry eu = entries[i];
hentry ev = entries[i + 1];
vertex u = vertices[eu.i_vertices];
u.indices[u.i_indices++] = ev.i_vertices;
}
hcleanup();
}
private void hinit(int size)
{
entries = new hentry[size];
for (int i = 0; i < size; i++)
{
entries[i] = new hentry();
}
htable = new hentry[size];
htablesize = size;
hmagic = (Math.Sqrt(5.0) - 1.0) / 2.0;
}
private void hinsert(int i_sequence)
{
int code = hcode(i_sequence);
hentry e, e2 = entries[i_sequence];
for (e = htable[code]; e != null; e = e.next)
{
if (strncmp(e.i_sequence, i_sequence, k_ - 1) == 0)
{
e2.i_sequence = e.i_sequence;
e2.i_vertices = e.i_vertices;
return;
}
}
e2.i_sequence = i_sequence;
e2.i_vertices = n_vertices++;
e2.next = htable[code];
htable[code] = e2;
}
