From cppreference.com
Defined in header
template<classForwardIt>std::pair<ForwardIt,ForwardIt>minmax_element(ForwardItfirst,ForwardItlast); (1)(since C++11)
(constexpr since C++17)template<classExecutionPolicy,classForwardIt>std::pair<ForwardIt,ForwardIt>minmax_element(ExecutionPolicy&&policy,ForwardItfirst,ForwardItlast); (2) (since C++17)template<classForwardIt,classCompare>std::pair<ForwardIt,ForwardIt>minmax_element(ForwardItfirst,ForwardItlast,Comparecomp); (3)(since C++11)
(constexpr since C++17)template<classExecutionPolicy,classForwardIt,classCompare>std::pair<ForwardIt,ForwardIt>minmax_element(ExecutionPolicy&&policy,ForwardItfirst,ForwardItlast,Comparecomp); (4) (since C++17)Finds the smallest and greatest element in the range [first, last).
1) Elements are compared using operator<(until C++20)std::less{}(since C++20).
3) Elements are compared using the comparison function comp.
2,4) Same as (1,3), but executed according to policy.
These overloads participate in overload resolution only if the value of the following expression is true:
std::is_execution_policy_v<std::decay_t<ExecutionPolicy>>
(until C++20)std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>>
(since C++20)Parameters
first, last - the pair of iterators defining the
of elements to examine policy - the
to use cmp - comparison function object (i.e. an object that satisfies the requirements of
) which returns true if the first argument is less than the second. The signature of the comparison function should be equivalent to the following:
boolcmp(constType1&a,constType2&b);
While the signature does not need to have const&, the function must not modify the objects passed to it and must be able to accept all values of type (possibly const) Type1 and Type2 regardless of
(thus, Type1& is not allowed, nor is Type1 unless for Type1 a move is equivalent to a copy(since C++11)).
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
. 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.
Complexity
Given N as std::distance(first,last):
1,2) At most max(⌊32(N-1)⌋,0) comparisons using operator<(until C++20)std::less{}(since C++20).
3,4) At most max(⌊32(N-1)⌋,0) applications of the comparison function comp.
Exceptions
The overloads with a template parameter named ExecutionPolicy report errors as follows:
If execution of a function invoked as part of the algorithm throws an exception and ExecutionPolicy is one of the
,
is called. For any other ExecutionPolicy, the behavior is implementation-defined.
If the algorithm fails to allocate memory,
is thrown.
Possible implementation
template<classForwardIt>std::pair<ForwardIt,ForwardIt>minmax_element(ForwardItfirst,ForwardItlast){usingvalue_type=typenamestd::iterator_traits<ForwardIt>::value_type;returnstd::minmax_element(first,last,std::less<value_type>());}
template<classForwardIt,classCompare>std::pair<ForwardIt,ForwardIt>minmax_element(ForwardItfirst,ForwardItlast,Comparecomp){automin=first,max=first;if(first==last||++first==last)return{min,max};if(comp(*first,*min))min=first;elsemax=first;while(++first!=last){autoi=first;if(++first==last){if(comp(*i,*min))min=i;elseif(!(comp(*i,*max)))max=i;break;}else{if(comp(*first,*i)){if(comp(*first,*min))min=first;if(!(comp(*i,*max)))max=i;}else{if(comp(*i,*min))min=i;if(!(comp(*first,*max)))max=first;}}}return{min,max};}Notes
This algorithm is different from std::make_pair(std::min_element(),std::max_element()), not only in efficiency, but also in that this algorithm finds the last biggest element while
finds the first biggest element.
Example
Run this code
#include<algorithm>#include<iostream>intmain(){constautov={3,9,1,4,2,5,9};constauto[min,max]=std::minmax_element(begin(v),end(v));std::cout<<"min = "<<*min<<", max = "<<*max<<'\n';}Output:
min = 1, max = 9 See also