std::partition
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Definido no cabeçalho <algorithm> | ||
template<class BidirIt, class UnaryPredicate > BidirectionalIterator partition( BidirIt first, BidirIt last, | (até C++11) (desde C++11) | |
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.
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Índice |
[editar]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: bool pred(const Type &a); The signature does not need to have const&, but the function must not modify the objects passed to it. |
| Type requirements | ||
-BidirIt must meet the requirements of BidirectionalIterator. | ||
-ForwardIt must meet the requirements of ValueSwappable and ForwardIterator. However, the operation is more efficient if ForwardIt also satisfies the requirements of BidirectionalIterator | ||
[editar]Valor de retorno
Iterador para o primeiro elemento do segundo grupo.
Original:
Iterator to the first element of the second group.
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[editar]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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[editar]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;} |
[editar]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 vectorstd::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
[editar]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) | |
