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    function template
    <algorithm>

    std::min_element

    namespace std {
      template<class ForwardIterator>
      ForwardIterator
        min_element(ForwardIterator first,
                    ForwardIterator last); // (1) C++03
    
      template<class ForwardIterator, class Compare>
      ForwardIterator
        min_element(ForwardIterator first,
                    ForwardIterator last,
                    Compare comp);         // (2) C++03
    
      template <class ExecutionPolicy, class ForwardIterator>
      ForwardIterator
        min_element(ExecutionPolicy&& exec,
                    ForwardIterator first,
                    ForwardIterator last); // (3) C++17
    
      template <class ExecutionPolicy, class ForwardIterator, class Compare>
      ForwardIterator
        min_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、最小要素を指す最初のイテレータを取得する。

    戻り値

    *i < *jもしくはcomp(*i, *j)の比較によって最小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)回の比較を行う

    #include <algorithm>
    #include <cassert>
    #include <utility>
    #include <vector>
    
    int main()
    {
      // (1)
      std::vector<int> v1 = {3, 1, 4};
    
      decltype(v1)::iterator v1_min_element = std::min_element(v1.begin(), v1.end());
      assert(*v1_min_element == 1);
    
    
      // (2)
      std::vector<std::pair<int, int>> v2 = {{0, 3}, {1, 1}, {2, 4}};
    
      decltype(v2)::iterator v2_min_element = std::min_element(v2.begin(), v2.end(), [](const auto& a, const auto& b) {
        return a.second < b.second;
      });
      assert(v2_min_element->first == 1);
      assert(v2_min_element->second == 1);
    }
    

    出力

    実装例

    template <class ForwardIterator>
    ForwardIterator min_element(ForwardIterator first, ForwardIterator last)
    {
      if (first == last)
        return first;
    
      ForwardIterator result = first++;
      for (; first != last; ++first) {
        if (*first < *result) {
          result = first;
        }
      }
      return result;
    }
    
    template <class ForwardIterator, class Compare>
    ForwardIterator min_element(ForwardIterator first, ForwardIterator last, Compare comp)
    {
      if (first == last)
        return first;
    
      ForwardIterator result = first++;
      for (; first != last; ++first) {
        if (comp(*first, *result)) {
          result = first;
        }
      }
      return result;
    }
    

    参照