C++ STL 알고리즘 (Algorithms)

STL 알고리즘 (Algorithms)

예제

• 클래스를 원소로 넣을 경우 대부분 비교 연산자 오버로딩을 해놔야 한다.

  #include <iostream>
  #include <vector>
  #include <algorithm>
  
  int            main()
  {
    using namespace std;
  
    vector<int> container;
    for (int i = 0; i < 10; ++i)
      container.push_back(i);
  
    auto itr = min_element(container.begin(), container.end());
    cout << "Min element : " << *itr << endl;
  
    itr = max_element(container.begin(), container.end());
    cout << "Max element : " << *itr << "\n\n";
  
    itr = find(container.begin(), container.end(), 3);
    container.insert(itr, 128);
  
    for (auto& e : container) cout << e << ' ';
    cout << endl;
  
    sort(container.begin(), container.end());
    for (auto& e : container) cout << e << ' ';
    cout << endl;
  
    reverse(container.begin(), container.end());
    for (auto& e : container) cout << e << ' ';
    cout << endl;
  }
  
  /* stdout stderr
  Min element : 0
  Max element : 9
  
  0 1 2 128 3 4 5 6 7 8 9
  0 1 2 3 4 5 6 7 8 9 128
  128 9 8 7 6 5 4 3 2 1 0
  */

  ---

• list의 경우 sort() 함수를 쓸 수 없고, 클래스 멤버 함수인 list::sort()를 사용해야 한다.

  #include <iostream>
  #include <list>
  #include <algorithm>
  
  int            main()
  {
    using namespace std;
  
    list<int> container;
    for (int i = 0; i < 10; ++i)
      container.push_back(i);
  
    auto itr = min_element(container.begin(), container.end());
    cout << "Min element : " << *itr << endl;
  
    itr = max_element(container.begin(), container.end());
    cout << "Max element : " << *itr << "\n\n";
  
    itr = find(container.begin(), container.end(), 3);
    container.insert(itr, 128);
  
    for (auto& e : container) cout << e << ' ';
    cout << endl;
  
    container.sort();
    for (auto& e : container) cout << e << ' ';
    cout << endl;
  
    container.reverse();
    for (auto& e : container) cout << e << ' ';
    cout << endl;
  }
  
  /* stdout stderr
  Min element : 0
  Max element : 9
  
  0 1 2 128 3 4 5 6 7 8 9
  0 1 2 3 4 5 6 7 8 9 128
  128 9 8 7 6 5 4 3 2 1 0
  */

---

참고

• https://en.cppreference.com/w/cpp/header/algorithm