exa/codecrypt
1
0
Fork 0
Code Issues Pull requests Actions Packages Projects Releases Wiki Activity

permutations

Browse source
This commit is contained in:
Mirek Kratochvil 2012-04-01 20:52:46 +02:00
parent dff9e91123
commit 859dd3ef82
1 changed files with 25 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

28
lib/permutation.cpp
View file

@ -5,21 +5,43 @@ using namespace ccr;
void permutation::compute_inversion (permutation&r)
{
r.resize (size(), 0);
for (uint i = 0; i < size(); ++i)
r[item (i) ] = i;
}
void permutation::generate_random (uint size, prng&rng)
{
resize (size, 0);
uint i;
for (i = 0; i < size; ++i) item (i) = i;
//knuth shuffle
for (i = size - 1; i > 0; --i) {
uint j = rng.random (i + 1);
if (i != j) {
uint t = item (i);
item (i) = item (j);
item (j) = t;
}
}
}
void permutation::permute_cols (const matrix&a, matrix&r)
void permutation::permute (const bvector&a, bvector&r)
{
r.resize (a.size() );
for (uint i = 0; i < size(); ++i) r[item (i) ] = a[i];
}
void permutation::permute (const matrix&a, matrix&r)
{
r.resize (a.size() );
for (uint i = 0; i < size(); ++i) r[item (i) ] = a[i];
}
void permutation::permute_rows (const matrix&a, matrix&r)
{
r.resize (a.size() );
for (uint i = 0; i < a.size(); ++i) permute (a[i], r[i]);
}