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std::minmax_element - cppreference.com

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Definido no cabeçalho

<algorithm>

template< class ForwardIt > std::pair<ForwardIt,ForwardIt> minmax_element( ForwardIt first, ForwardIt last );

 (1)

template< class ForwardIt, class Compare > std::pair<ForwardIt,ForwardIt> minmax_element( ForwardIt first, ForwardIt last, Compare comp );

 (2)

Encontra o maior e o mais pequeno elemento na [first, last) gama. A primeira versão utiliza operator< para comparar os valores, a segunda versão utiliza a função de comparação dada comp.

Original:

Finds the greatest and the smallest element in the range [first, last). The first version uses operator< to compare the values, the second version uses the given comparison function comp.

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Parâmetros

first, last -

iteradores para a frente que definem o intervalo para examinar

Original:

forward iterators defining the range to examine

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cmp - comparison function which returns ​true if if *a is less than *b.

The signature of the comparison function should be equivalent to the following:

bool cmp(const Type1 &a, const Type2 &b);

The signature does not need to have const &, but the function must not modify the objects passed to it.
The types Type1 and Type2 must be such that an object of type ForwardIt can be dereferenced and then implicitly converted to both of them. ​

Type requirements
-ForwardIt must meet the requirements of ForwardIterator.

Valor de retorno

um par consistindo de uma iteração para o elemento mais pequeno, como o primeiro elemento e um iterador para o elemento maior que a segunda. Retorna std::make_pair(first, first) se o intervalo está vazio. Se vários elementos são equivalentes ao elemento mais pequeno, o iterador para o primeiro elemento tal é retornada. Se vários elementos são equivalentes ao elemento maior, o iterador para o último elemento tal for devolvido.

Original:

a pair consisting of an iterator to the smallest element as the first element and an iterator to the greatest element as the second. Returns std::make_pair(first, first) if the range is empty. If several elements are equivalent to the smallest element, the iterator to the first such element is returned. If several elements are equivalent to the largest element, the iterator to the last such element is returned.

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Complexidade

Na maioria das aplicações de max(floor(3/2(N−1)), 0) do predicado, onde N = std::distance(first, last).

Original:

At most max(floor(3/2(N−1)), 0) applications of the predicate, where N = std::distance(first, last).

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Possível implementação

First version 
template<class ForwardIt>
std::pair<ForwardIt, ForwardIt> 
    minmax_element(ForwardIt first, ForwardIt last)
{
    typedef typename std::iterator_traits<ForwardIt>::value_type value_t;
    return std::minmax_element(first, last, std::less<value_t>());
}
Second version 
template<class ForwardIt, class Compare>
std::pair<ForwardIt, ForwardIt> 
    minmax_element(ForwardIt first, ForwardIt last, Compare comp)
{
    std::pair<ForwardIt, ForwardIt> result(first, first);
    
    if (first == last) return result;
    if (++first == last) return result;

    if (comp(*first, *result.first)) {
        result.second = result.first;
        result.first = first;
    } else {
        result.second = first;
    }
    while (++first != last) {
        ForwardIt i = first;
        if (++first == last) {
            if (comp(*i, *result.first)) result.first = i;
            else if (!(comp(*i, *result.second))) result.second = i;
            break;
        } else {
            if (comp(*first, *i)) {
                if (comp(*first, *result.first)) result.first = first;
                if (!(comp(*i, *result.second))) result.second = i;
            } else {
                if (comp(*i, *result.first)) result.first = i;
                if (!(comp(*first, *result.second))) result.second = first;
            }
        }
    }
    return result;
}

Exemplo

#include <algorithm>
#include <iostream>
#include <vector>
 
int main()
{
    std::vector<int> v = { 3, 9, 1, 4, 2, 5, 9 };
 
    auto result = std::minmax_element(v.begin(), v.end());
    std::cout << "min element at: " << (result.first - v.begin()) << '\n';
    std::cout << "max element at: " << (result.second - v.begin()) << '\n';
}

Saída: 

min element at: 2
max element at: 6

Veja também

retorna o elemento mais pequeno de um intervalo

Original:

returns the smallest element in a range

The text has been machine-translated via Google Translate.
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(modelo de função) [edit]

retorna o maior elemento de um intervalo

Original:

returns the largest element in a range

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) [edit]