Pair in c++/cpp Standard Template Library(STL) Almost Everything

 Almost everything about Pair in c++ note

Created by ujjal roy

Declaration pair in cpp/c++

#include<bits/stdc++.h>

using namespace std;

main()

{

    pair<int , int> p;

    pair<string , int> q;

    pair<int , vector<int>> r;

    p.first=3;

    p.second=5;

    q.first="ujjal";

    q.second=4;

   cout<<p.first<<" "<<p.second<<endl;

    r.first=6;

    r.second={1,2,3};

    cout<<r.first<<endl;

    for(auto v: r.second) cout<<v<<" ";

    return 0;

}

User Input Pair in c++ / cpp

#include<bits/stdc++.h>

using namespace std;

main()

{

     pair<int , int> p;

     cin>>p.first>>p.second;

     cout<<p.first<<" "<<p.second<<endl;

}

C++ make_pair example pair operation pair function

#include<bits/stdc++.h>

using namespace std;

main()

{

    pair<int , int>p;

    pair<int ,int> q;

    pair<string ,vector<int>> r;

       q={4,5};

    p=make_pair(2,3);

    r={"ujjal", {1,2,3,4,5}};

cout<<p.first<<" "<<p.second<<endl;

 p.first++;

 cout<<p.first<<" "<<p.second<<endl;

cout<<q.first<<" "<<q.second<<endl;

cout<<"pair r string and vector"<<endl;

cout<<r.first<<" "<<r.second.size()<<endl;

    return 0;

}

pair operation with example

#include<bits/stdc++.h>

using namespace std;

main()

{

    pair<int ,int> p;

    pair<int ,int> q;

    pair<int ,int> r;

    p={4,5};

    q={3,6};

    if(p>q) cout<<"P is greater than Q"<<endl;

    else if(p<q) cout<<"Q is greater than P"<<endl;

    else cout<<"both are equal;"<<endl;

    r=min(p,q);

    cout<<r.first<<" "<<r.second<<endl;

     r=max(p,q);

    cout<<r.first<<" "<<r.second<<endl;

    return 0;

}

Sorting Vector of Pair 

#include<bits/stdc++.h>

using namespace std;

main()

{

    vector<pair<int , int>>v;

    v.push_back({1,2});

    v.push_back({2,2});

    v.push_back({3,2});

    v.push_back({6,5});

    v.push_back({6,4});

    sort(v.begin(),v.end());

    cout<<"Increasing order "<<endl;

    for(auto u : v) cout<<u.first<<" "<<u.second<<endl;

      sort(v.rbegin(),v.rend());

      cout<<"Decreasing order "<<endl;

     for(auto u : v) cout<<u.first<<" "<<u.second<<endl;

    return 0;

}

Array of Pair in c++

#include<bits/stdc++.h>

using namespace std;

main()

{

    pair<int , int> p[]={{3,5},{3,6},{4,5},{5,5}};

    sort(p,p+4);

    for(int i=0;i<4;i++) cout<<p[i].first<<" "<<p[i].second<<endl;

    return 0;

}

Vector of Pair unique function

#include<bits/stdc++.h>

using namespace std;

main()

{

    vector<pair<int , int>> v;

    v.push_back({1,4});

    v.push_back({1,5});

    v.push_back({1,1});

    v.push_back({2,4});

    v.push_back({1,4});

   sort(v.begin(),v.end());

   int size=unique(v.begin(),v.end())-v.begin();

   for(int i=0;i<size;i++) cout<<v[i].first<<" "<<v[i].second<<endl;

    return 0;

}