mirror of
https://github.com/biergaizi/codecrypt
synced 2024-06-16 11:58:16 +00:00
48 lines
1.2 KiB
C++
48 lines
1.2 KiB
C++
|
|
/*
|
|
* This file is part of Codecrypt.
|
|
*
|
|
* Copyright (C) 2013-2016 Mirek Kratochvil <exa.exa@gmail.com>
|
|
*
|
|
* Codecrypt is free software: you can redistribute it and/or modify it
|
|
* under the terms of the GNU Lesser General Public License as published by
|
|
* the Free Software Foundation, either version 3 of the License, or (at
|
|
* your option) any later version.
|
|
*
|
|
* Codecrypt is distributed in the hope that it will be useful, but WITHOUT
|
|
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
|
|
* License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public License
|
|
* along with Codecrypt. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include "permutation.h"
|
|
#include "prng.h"
|
|
#include "matrix.h"
|
|
|
|
void permutation::compute_inversion (permutation&r) const
|
|
{
|
|
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;
|
|
}
|
|
}
|
|
}
|