std::is_permutation
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<tbody> </tbody>| Déclaré dans l'en-tête <algorithm>
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template< class ForwardIt1, class ForwardIt2 > bool is_permutation( ForwardIt1 first, ForwardIt1 last, ForwardIt2 d_first ); |
(1) | (depuis C++11) |
template< class ForwardIt1, class ForwardIt2, class BinaryPredicate > bool is_permutation( ForwardIt1 first, ForwardIt1 last, ForwardIt2 d_first, BinaryPredicate p ); |
(2) | (depuis C++11) |
Retours
true s'il existe une permutation des éléments de la gamme [first1, last1) qui rend cet intervalle égal à l'intervalle commençant à d_first. La première version utilise operator== pour l'égalité, la deuxième version utilise le p prédicat binaireOriginal:
Returns
true if there exists a permutation of the elements in the range [first1, last1) that makes that range equal to the range beginning at d_first. The first version uses operator== for equality, the second version uses the binary predicate pThe text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
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Paramètres
| first, last | - | la plage d'éléments à comparer
Original: the range of elements to compare The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| d_first | - | le début de la deuxième plage de comparer
Original: the beginning of the second range to compare The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| p | - | binary predicate which returns true if the elements should be treated as equal. The signature of the predicate function should be equivalent to the following:
The signature does not need to have |
| Type requirements | ||
-ForwardIt1, ForwardIt2 must meet the requirements of ForwardIterator.
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Retourne la valeur
true si le [first, last) plage est une permutation de la gamme débutant à d_first .Original:
true if the range [first, last) is a permutation of the range beginning at d_first.The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Complexité
À la plupart des applications O(N2) du prédicat, ou exactement N si les séquences sont déjà égaux, où
N=std::distance(first, last) .Original:
At most O(N2) applications of the predicate, or exactly N if the sequences are already equal, where
N=std::distance(first, last).The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
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Mise en œuvre possible
template<class ForwardIt1, class ForwardIt2>
bool is_permutation(ForwardIt1 first, ForwardIt1 last,
ForwardIt2 d_first)
{
// skip common prefix
std::tie(first, d_first) = std::mismatch(first, last, d_first);
// iterate over the rest, counting how many times each element
// from [first, last) appears in [d_first, d_last)
if (first != last) {
ForwardIt2 d_last = d_first;
std::advance(d_last, std::distance(first, last));
for (ForwardIt1 i = first; i != last; ++i) {
if (i != std::find(first, i, *i)) continue; // already counted this *i
auto m = std::count(d_first, d_last, *i);
if (m==0 || std::count(i, last, *i) != m) {
return false;
}
}
}
return true;
}
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Exemple
#include <algorithm>
#include <vector>
#include <iostream>
int main()
{
std::vector<int> v1{1,2,3,4,5};
std::vector<int> v2{3,5,4,1,2};
std::cout << "3,5,4,1,2 is a permutation of 1,2,3,4,5? "
<< std::boolalpha
<< std::is_permutation(v1.begin(), v1.end(), v2.begin()) << '\n';
std::vector<int> v3{3,5,4,1,1};
std::cout << "3,5,4,1,1 is a permutation of 1,2,3,4,5? "
<< std::boolalpha
<< std::is_permutation(v1.begin(), v1.end(), v3.begin()) << '\n';
}
Résultat :
3,5,4,1,2 is a permutation of 1,2,3,4,5? true
3,5,4,1,1 is a permutation of 1,2,3,4,5? false
Voir aussi
génère la plus grande lexicographique prochaine permutation d'un ensemble d'éléments Original: generates the next greater lexicographic permutation of a range of elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction générique) | |
lexicographique génère le plus petit côté d'une permutation série d'éléments Original: generates the next smaller lexicographic permutation of a range of elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction générique) | |