std::minmax_element
From Cppreference
| Defined in header <algorithm>
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| template< class ForwardIterator >
std::pair<ForwardIterator,ForwardIterator> |
(1) | |
| template< class ForwardIterator, class Compare >
std::pair<ForwardIterator,ForwardIterator> |
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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.
Contents |
[edit] Parameters
| first, last | - | forward iterators defining the range to examine | |||||||||
| 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:
The signature does not need to have const &, but the function must not modify the objects passed to it. |
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[edit] Return value
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.
[edit] Complexity
At most max(floor(3/2(N−1)), 0) applications of the predicate, where N = std::distance(first, last).
[edit] Equivalent function
| First version |
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template<class ForwardIterator> std::pair<ForwardIterator, ForwardIterator> minmax_element(ForwardIterator first, ForwardIterator last) { typedef typename std::iterator_traits<ForwardIterator>::value_type value_t; return std::minmax_element(first, last, std::less<value_t>()); } |
| Second version |
template<class ForwardIterator, class Compare> std::pair<ForwardIterator, ForwardIterator> minmax_element(ForwardIterator first, ForwardIterator last, Compare comp) { std::pair<ForwardIterator, ForwardIterator> 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) { ForwardIterator 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; } |
[edit] Example
#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'; }
Output:
min element at: 2 max element at: 6
[edit] See also
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returns the smallest element in a range (function template) |
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returns the largest element in a range (function template) |
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