sets_multisets_practise

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;

int main()
{
    // 1.>basics of C++
    // 2.>basics of for/while/do while loops
    // 3.>basics of implementation/ arrays etc
    // 4.>recursion
    // 5.>binary search
    // 6.>searching/sorting techniques
    //stl techniques(vectors,maps,pairs)
    //prefix sum (technique)

    // 7.>hashing
    // 8.>two pointers
    // 9.>stacks_queues


    //lot of practise through contests and questions
    // 10. > sets
    // 11. > multisets
    // 12. > questions
    // 13. > sliding window technique
    //questions of mixed variety of all the concepts studied till here

    // 14. > strings algorithms
    // 15. > greedy algorithms
    // 16. > bits manipulation


    set<int> s;
    s.insert(100); s.insert(1000);
    s.insert(20); s.insert(2);
    // cout << s.size() << endl;

    //iteration
    // for (auto it = s.begin(); it != s.end(); it++)
    // {
    //  cout << *it << " " << endl;
    // }
    // cout << endl;
    for (auto i : s)
    {
        cout << i << " " << endl;
    }

    // cout << endl;


    // cout << *(s.begin()) << endl;


    //iteration and iterators and how to insert in set


    //how to find or check an element in the set
    int x; cin >> x;
    if (s.find(x) == s.end())
    {
        cout << "NOT FOUND" << endl;
    }
    else cout << "FOUND" << endl;


    //how to erase a element in the set

    s.erase(s.find(x));

    for (auto i : s)
    {
        cout << i << endl;
    }


    //////////////////////////////////////////////////////////////////////////////


    // multiset<ll> m1; //store in ascending order

    // m1.insert(10); m1.insert(20); m1.insert(1); m1.insert(10);
    // for (auto i : m1) cout << i << " "; cout << endl;

    // cout << m1.count(10) << endl;//frequency of 10

    // m1.erase(10);//erased all instances/occurences of 10
    // for (auto i : m1) cout << i << " "; cout << endl;

    // m1.insert(10); m1.insert(10);
    // for (auto i : m1) cout << i << " "; cout << endl;

    // m1.erase(m1.find(10));//erased only single instance of 10
    // for (auto i : m1) cout << i << " "; cout << endl;

    // auto it1 = m1.begin();
    // cout << *it1 << endl << endl << endl; //or*m1.begin()
///////////////////////////////////////////////////////////////////////////////////////

    multiset<ll, greater<ll>> m2; //store in descending order

    m2.insert(10); m2.insert(20); m2.insert(1); m2.insert(10);
    for (auto i : m2) cout << i << " "; cout << endl;

    cout << m2.count(10) << endl;//ferqeuency of 10

    m2.erase(10);//erased all instances of 10
    for (auto i : m2) cout << i << " "; cout << endl;

    m2.insert(10); m2.insert(10);
    for (auto i : m2) cout << i << " "; cout << endl;

    m2.erase(m2.find(10));//erased only single instance of 10
    for (auto i : m2) cout << i << " "; cout << endl;

    auto it2 = m2.begin();
    cout << *it2 << endl;//or*m2.begin()


    return 0;
}