/usr/include/wfmath-1.0/wfmath/shuffle.h is in libwfmath-1.0-dev 1.0.2+dfsg1-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 | // randgen.h (random number functions)
//
// The WorldForge Project
// Copyright (C) 2002 The WorldForge Project
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
// For information about WorldForge and its authors, please contact
// the Worldforge Web Site at http://www.worldforge.org.
// Author: Ron Steinke
// Created: 2002-5-23
#ifndef WFMATH_SHUFFLE_H
#define WFMATH_SHUFFLE_H
#include <wfmath/MersenneTwister.h>
#include <vector>
namespace WFMath {
/// Randomly reorder the contents of a std::vector
/**
* For things like shuffling a deck of cards, etc.
**/
template<class C>
void Shuffle(std::vector<C>& v) // need vector for random access
{
typedef typename std::vector<C>::size_type size_type;
size_type pos = v.size();
if(!pos) // handle size() == 0 nicely
return;
// This swaps each element with one of the ones before
// it, starting with the last element. Essentially,
// this generates an operation from the permutation
// group of size() elements, and applies it to the
// vector. Note that the loop only executes size() - 1
// times, as element 0 has nothing to swap with.
while(--pos) {
size_type new_pos = MTRand::instance.randInt(pos); // 0 <= new_pos <= pos
if(new_pos == pos)
continue;
C tmp = v[pos];
v[pos] = v[new_pos];
v[new_pos] = tmp;
}
}
} // namespace WFMath
#endif // WFMATH_SHUFFLE_H
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