36 lines
639 B
C++
36 lines
639 B
C++
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#include "codecrypt.h"
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using namespace ccr;
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void permutation::compute_inversion (permutation&r) const
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{
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r.resize (size(), 0);
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for (uint i = 0; i < size(); ++i)
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r[item (i) ] = i;
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}
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void permutation::generate_random (uint size, prng&rng)
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{
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resize (size, 0);
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uint i;
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for (i = 0; i < size; ++i) item (i) = i;
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//knuth shuffle
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for (i = size - 1; i > 0; --i) {
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uint j = rng.random (i + 1);
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if (i != j) {
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uint t = item (i);
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item (i) = item (j);
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item (j) = t;
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}
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}
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}
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void permutation::permute_rows (const matrix&a, matrix&r) const
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{
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r.resize (a.size() );
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for (uint i = 0; i < a.size(); ++i) permute (a[i], r[i]);
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}
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