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最終更新日時:
2026年08月25日 12時11分17秒 (JST)
Akira Takahashi
が更新
function template
<algorithm>
std:: max_element
namespace std {
template < class ForwardIterator >
ForwardIterator
max_element ( ForwardIterator first ,
ForwardIterator last ); // (1) C++98
template < class ForwardIterator , class Compare >
ForwardIterator
max_element ( ForwardIterator first ,
ForwardIterator last ,
Compare comp ); // (2) C++98
template < class ExecutionPolicy , class ForwardIterator >
ForwardIterator
max_element ( ExecutionPolicy && exec ,
ForwardIterator first ,
ForwardIterator last ); // (3) C++17
template < class ExecutionPolicy , class ForwardIterator , class Compare >
ForwardIterator
max_element ( ExecutionPolicy && exec ,
ForwardIterator first ,
ForwardIterator last ,
Compare comp ); // (4) C++17
}
概要
イテレータ範囲[first, last)のうち、最大要素を指す最初のイテレータを取得する。
戻り値
*j < *iもしくはcomp(*j, *i)の比較によって最大と判断された最初の要素を指すイテレータを返す。
計算量
max ((last - first) - 1, 0)
例
#include <algorithm>
#include <cassert>
#include <utility>
#include <vector>
int main ()
{
// (1)
std::vector < int > v1 = { 3 , 1 , 4 };
decltype ( v1 ) :: iterator v1_max_element = std::max_element ( v1.begin() , v1.end() );
assert ( * v1_max_element == 4 );
// (2)
std::vector < std::pair < int , int >> v2 = {{ 0 , 3 }, { 1 , 1 }, { 2 , 4 }};
decltype ( v2 ) :: iterator v2_max_element = std::max_element ( v2.begin() , v2.end() , []( const auto & a , const auto & b ) {
return a . second < b . second ;
});
assert ( v2_max_element -> first == 2 );
assert ( v2_max_element -> second == 4 );
}
出力
実装例
template < class ForwardIterator >
ForwardIterator max_element ( ForwardIterator first , ForwardIterator last )
{
if ( first == last )
return first ;
ForwardIterator result = first ++ ;
for (; first != last ; ++ first ) {
if ( * result < * first ) {
result = first ;
}
}
return result ;
}
template < class ForwardIterator , class Compare >
ForwardIterator max_element ( ForwardIterator first , ForwardIterator last , Compare comp )
{
if ( first == last )
return first ;
ForwardIterator result = first ++ ;
for (; first != last ; ++ first ) {
if ( comp ( * result , * first )) {
result = first ;
}
}
return result ;
}
関連項目
参照