std::partition
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<tbody> </tbody>| Definido no cabeçalho <algorithm>
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template< class BidirIt, class UnaryPredicate > BidirectionalIterator partition( BidirIt first, BidirIt last, UnaryPredicate p ); template< class ForwardIt, class UnaryPredicate > ForwardIt partition( ForwardIt first, ForwardIt last, UnaryPredicate p ); |
(até C++11) (desde C++11) |
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Reordena os elementos na
[first, last) faixa, de tal modo que todos os elementos para os quais o predicado p retornos true precedem os elementos para os quais predicado p retornos false. Ordem relativa dos elementos não é preservada. Original:
Reorders the elements in the range
[first, last) in such a way that all elements for which the predicate p returns true precede the elements for which predicate p returns false. Relative order of the elements is not preserved. 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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Parâmetros
| first, last | - | a gama de elementos para reordenar
Original: the range of elements to reorder The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| p | - | unary predicate which returns true se o elemento deve ser solicitado antes de outros elementos . Original: if the element should be ordered before other elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. The signature of the predicate function should be equivalent to the following:
The signature does not need to have |
| Type requirements | ||
-BidirIt must meet the requirements of BidirectionalIterator.
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-ForwardIt must meet the requirements of ValueSwappable and ForwardIterator. However, the operation is more efficient if ForwardIt also satisfies the requirements of BidirectionalIterator
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Valor de retorno
Iterador para o primeiro elemento do segundo grupo.
Original:
Iterator to the first element of the second group.
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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Complexidade
Exatamente
last-first aplicações do predicado e em swaps maioria last-first. Se ForwardIt cumpre os requisitos da BidirectionalIterator em swaps maioria (last-first)/2 são feitas.Original:
Exactly
last-first applications of the predicate and at most last-first swaps. If ForwardIt meets the requirements of BidirectionalIterator at most (last-first)/2 swaps are done.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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Possível implementação
template<class BidirIt, class UnaryPredicate>
BidirIt partition(BidirIt first, BidirIt last, UnaryPredicate p)
{
while (1) {
while ((first != last) && p(*first)) {
++first;
}
if (first == last--) break;
while ((first != last) && !p(*last)) {
--last;
}
if (first == last) break;
std::swap(*first++, *last);
}
return first;
}
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Exemplo
#include <algorithm>
#include <functional>
#include <iostream>
#include <iterator>
#include <vector>
bool is_even(int i) { return i % 2 == 0; }
int main()
{
std::vector<int> v;
for (int i = 0; i < 10; ++i) v.push_back(i);
std::cout << "Original vector:\n ";
std::copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));
// Partition the vector
std::vector<int>::iterator p =
std::partition(v.begin(), v.end(), std::ptr_fun(is_even));
std::cout << "\nPartitioned vector:\n ";
std::copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));
std::cout << "\nBefore partition:\n ";
std::copy(v.begin(), p, std::ostream_iterator<int>(std::cout, " "));
std::cout << "\nAfter partition:\n ";
std::copy(p, v.end(), std::ostream_iterator<int>(std::cout, " "));
}
Potencial saída:
Original vector:
0 1 2 3 4 5 6 7 8 9
Partitioned vector:
0 8 2 6 4 5 3 7 1 9
Before partition:
0 8 2 6 4
After partition:
5 3 7 1 9
Veja também
(C++11) |
determina se o intervalo é dividido pelo predicado dado Original: determines if the range is partitioned by the given predicate The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de função) |
divide os elementos em dois grupos, preservando sua ordem relativa Original: divides elements into two groups while preserving their relative order The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de função) | |