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Replace hand-rolled loop with 'iota_n' and back_insert_iterator

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Marshall Clow
2023-06-25 20:32:15 -07:00
parent 25ab833cae
commit 62922bd1ff
1 changed files with 6 additions and 4 deletions
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10
include/boost/algorithm/indirect_sort.hpp
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@ -18,6 +18,8 @@
#include <functional> // for std::less #include <functional> // for std::less
#include <vector> // for std::vector #include <vector> // for std::vector
#include <boost/algorithm/cxx11/iota.hpp>
namespace boost { namespace algorithm { namespace boost { namespace algorithm {
typedef std::vector<size_t> Permutation; typedef std::vector<size_t> Permutation;
@ -37,15 +39,15 @@ namespace detail {
Iter iter_; Iter iter_;
}; };
// Initialize a permutation // Initialize a permutation of size 'size'. [ 0, 1, 2, ... size-1 ]
// it would be nice to use 'iota' here, but that call writes over // Note: it would be nice to use 'iota' here, but that call writes over
// existing elements - not append them. I don't want to initialize // existing elements - not append them. I don't want to initialize
// the elements of the permutation to zero, and then immediately // the elements of the permutation to zero, and then immediately
// overwrite them. // overwrite them.
void init_permutation (Permutation &p, size_t size) { void init_permutation (Permutation &p, size_t size) {
p.reserve(size); p.reserve(size);
for (size_t i = 0; i < size; ++i) boost::algorithm::iota_n(
p.push_back(i); std::back_insert_iterator<Permutation>(p), size_t(0), size);
} }
} }