std::max_element

 

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all_of any_of none_of (C++11) (C++11) (C++11) for_each count count_if mismatch equal	find find_if find_if_not (C++11) find_end find_first_of adjacent_find search search_n
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is_partitioned (C++11) partition partition_copy (C++11)	stable_partition partition_point (C++11)
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is_sorted (C++11) is_sorted_until (C++11) sort	partial_sort partial_sort_copy stable_sort nth_element
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max max_element min min_element minmax (C++11) minmax_element (C++11)	lexicographical_compare is_permutation (C++11) next_permutation prev_permutation
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iota (C++11) accumulate inner_product	adjacent_difference partial_sum
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qsort	bsearch

 

Заголовочный файл <algorithm>
template< class ForwardIt > ForwardIt max_element( ForwardIt first, ForwardIt last );	(1)
template< class ForwardIt, class Compare > ForwardIt max_element( ForwardIt first, ForwardIt last, Compare comp );	(2)

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

Параметры

first, last	-	вперед итераторы определении диапазона для изучения Original: forward iterators defining the range to examine The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
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.

Возвращаемое значение

Iterator to the greatest element in the range [first, last). If several elements in the range are equivalent to the greatest element, returns the iterator to the first such element. Returns last if the range is empty.

Сложность

Именно max(N-1,0) сравнений, где N = std::distance(first, last).

Original:

Exactly max(N-1,0) comparisons, 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.

Возможная реализация

First version
template<class ForwardIt> ForwardIt max_element(ForwardIt first, ForwardIt last) { if (first == last) { return last; } ForwardIt largest = first; ++first; for (; first != last; ++first) { if (*largest < *first) { largest = first; } } return largest; }
Second version
template<class ForwardIt, class Compare> ForwardIt max_element(ForwardIt first, ForwardIt last, Compare comp) { if (first == last) { return last; } ForwardIt largest = first; ++first; for (; first != last; ++first) { if (comp(*largest, *first)) { largest = first; } } return largest; }

Пример

#include <algorithm>
#include <iostream>
#include <vector>
#include <cmath>
 
static bool abs_compare(int a, int b)
{
    return (std::abs(a) < std::abs(b));
}
 
int main()
{
    std::vector<int> v{ 3, 1, -14, 1, 5, 9 };
    std::vector<int>::iterator result;
 
    result = std::max_element(v.begin(), v.end());
    std::cout << "max element at: " << std::distance(v.begin(), result) << '\n';
 
    result = std::max_element(v.begin(), v.end(), abs_compare);
    std::cout << "max element (absolute) at: " << std::distance(v.begin(), result);
}

Вывод:

max element at: 5
max element (absolute) at: 2

См. также

min_element	возвращает наименьший элемент в диапазоне Original: returns the smallest 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. (шаблон функции)
minmax_element (C++11)	возвращает наименьший и наибольший элемент в диапазоне Original: returns the smallest and 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. (шаблон функции)
max	Возвращает большее из двух элементов Original: returns the larger of two elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (шаблон функции)