[C++] 알고리즘

개요

• sort
• stable_sort
• partial_sort
  • partial_sort(a, b, c);
  • a부터 c까지의 데이터 중에 b 까지만 정렬
• remove, remove_if
• transform

예제

• 코드

  • #include <algorithm>
    #include <iostream>
    #include <vector>
           
    using namespace std;
           
    class Test {
        private:
            int i;
            char c;
           
        public:
            Test(int i, char c) : i(i), c(c) {}
            ~Test() = default;
           
            int GetI() const { return this->i; }
            void SetI(const int& i) { this->i = i; }
           
            bool operator<(const Test& t) const { return this->i < t.i; }
            bool operator==(const Test& t) const { return this->i == t.i; }
           
            friend ostream& operator<<(std::ostream& o, const Test& t);
    };
    ostream& operator<<(std::ostream& o, const Test& t) {
        o << t.i << ", " << t.c;
        return o;
    }
           
    void make_data(vector<Test>& v, const int& count = 100) {
        v.clear();
           
        for (int i = count; i > 0; --i) {
            v.push_back(Test(i % 10, 'a' + i % 26));
        }
    }
           
    int main() {
        vector<Test> v;
           
        make_data(v);
        sort(v.begin(), v.end());
        for (int i = 0; i < 5; ++i) {
            cout << "v-1 : " << v.at(i) << endl;
        }
           
        make_data(v);
        stable_sort(v.begin(), v.end());
        for (int i = 0; i < 5; ++i) {
            cout << "v-2 : " << v.at(i) << endl;
        }
           
        make_data(v, 5);
        partial_sort(v.begin(), v.begin() + 2, v.end());
        for (const auto& iter : v) {
            cout << "v-3 : " << iter << endl;
        }
           
        make_data(v, 5);
        v.erase(remove(v.begin(), v.end(), Test(1, 'a')), v.end());
        for (const auto& iter : v) {
            cout << "v-4 : " << iter << endl;
        }
        v.erase(remove_if(v.begin(), v.end(), [](const Test& t) { return t.GetI() > 3; }),
                v.end());
        for (const auto& iter : v) {
            cout << "v-5 : " << iter << endl;
        }
           
        make_data(v, 5);
        transform(v.begin(), v.end(), v.begin(), [](Test& t) {
            t.SetI(t.GetI() + 1);
            return t;
        });
        for (const auto& iter : v) {
            cout << "v-6 : " << iter << endl;
        }
           
        return 0;
    }
    

• 실행 결과

  • v-1 : 0, w
    v-1 : 0, k
    v-1 : 0, u
    v-1 : 0, c
    v-1 : 0, e
    v-2 : 0, w
    v-2 : 0, m
    v-2 : 0, c
    v-2 : 0, s
    v-2 : 0, i
    v-3 : 1, b
    v-3 : 2, c
    v-3 : 5, f
    v-3 : 4, e
    v-3 : 3, d
    v-4 : 5, f
    v-4 : 4, e
    v-4 : 3, d
    v-4 : 2, c
    v-5 : 3, d
    v-5 : 2, c
    v-6 : 6, f
    v-6 : 5, e
    v-6 : 4, d
    v-6 : 3, c
    v-6 : 2, b