cpp-stl-cheatsheet.md

title	CPP-STL CheatSheet
description	Some STL library are implemented here.
created	2022-10-22

Table of Contents

• CPP STL CheatSheet for Developers
  • Vector
    • Vector insertion
    • Vector Display
    • Vector Maximum element
    • Vector Minimum element
    • Vector sort
    • Vector reverse
    • Vector deletion
  • Set
    • Set insertion
    • Set Display
  • Unordered Set
    • Unordered insertion
    • Unordered Display
  • Map
    • Map insertion
    • Map Display
  • Stack
    • Stack insertion
    • Stack Display
  • Queue
    • Queue insertion
    • Queue Display
  • Deque
    • Deque insertion
    • Deque Display
  • Vector Pair
    • Vector pair insertion
    • Vector pair Display
  • List
    • List insertion
    • List Display
    • List deletion
  • Priority Queue
    • Priority Queue insertion
    • Priority Queue Display

C++ STL CheatSheet for Developers

Vector

    // Vector  initialization 
    vector <int> v;
    
    // Vector  Insertion element
    cout << "Insertion of element in vector: " << endl;
    cout << endl;

    for (int i = 0; i < n; i++)
    {
        v.push_back(a[i]);
    }
    
    // Vector  Display element
    cout << "Display element of vector " << endl;

    for (int i = 0; i < n; i++)
    {
        cout << v[i] << " ";
    }
    cout << endl;
    
    // Vector maximum element
    int maximum = *max_element(v.begin(), v.end());
    
    // Vector minimum element
    int minimum = *min_element(v.begin(), v.end());

    cout << "Maximum element in vector " << maximum << endl;
    cout << "Minimum element in vector " << minimum << endl;
    sort(v.begin(), v.end());

    // Vector sort element
    cout << "Sort element of vector " << endl;
    for (int i = 0; i < n; i++)
    {
        cout << v[i] << " ";
    }
    reverse(v.begin(), v.end());
    cout << endl;

    // Vector reverse element
    cout << "Reverse element of vector " << minimum << endl;
    for (int i = 0; i < n; i++)
    {
        cout << v[i] << " ";
    }
    cout << endl;

    // Vector deletion
    cout << "Delete last element of vector " << endl;
    v.pop_back();
    for (int i = 0; i < n; i++)
    {
        cout << v[i] << " ";
    }

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Set

    // Set initialization 
    set <int> s;
    cout << endl;

    // Set insertion 
    cout << "Insertion in set " << endl;
    cout << endl;

    for (int i = 0; i < n; i++)
    {
        s.insert(a[i]);
    }

    // Set display
    cout << "Display of set element" << endl;

    for (auto i = s.begin(); i != s.end(); i++)
    {
        cout << *i << " ";
    }

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Unordered-Set

    // Unordered Set initialization 
    unordered_set <int> s1;
    cout << endl;
    
    // Unordered set insertion 
    cout << "Insertion in unordered set " << endl;

    for (int i = 0; i < n; i++)
    {
        s1.insert(a[i]);
    }
    
    // Unordered set display
    cout << "Display of unordered set element" << endl;

    for (auto i = s1.begin(); i != s1.end(); i++)
    {
        cout << *i << " ";
    }

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Map

    // Map initialization 
    map <int, int> m;
    cout << endl;
    
    // Map insertion
    cout << "Insertion in map " << endl;
    for (int i = 0; i < n; i++)
    {
        m[a[i]]++;
    }
    cout << "Display of map element" << endl;
    
    // Map display
    for (auto i = m.begin(); i != m.end(); i++)
    {
        cout << i->first << " " << i->second << endl;
    }  

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Stack

    // Stack initialization 
    stack<int> st;
    cout << endl;

    // Stack insertion
    cout << "Insertion in stack " << endl;

    for (int i = 0; i < n; i++)
    {
        st.push(a[i]);
    }
    
    // Stack display
    cout << "Display and removal of stack element" << endl;

    for (auto i = s.begin(); i != s.end(); i++)
    {
        cout << st.top() << " ";
        st.pop();
    } 

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Queue

    // Queue initialization 
	queue<int> q;
    cout << endl;

    // Queue insertion
    cout << "Insertion in queue " << endl;

    for (int i = 0; i < n; i++)
    {
        q.push(a[i]);
    }
    
    // Queue display
    cout << "Display of queue element" << endl;

    for (auto i = s.begin(); i != s.end(); i++)
    {
        cout << q.front() << " ";
        q.pop();
    }

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Deque

    // Deque initialization 
    deque <int> d;

    // Deque insertion
    cout << "Insertion in deqeue " << endl;

    for (int i = 0; i < n; i++)
    {
        d.push_front(a[i]);
    }
    cout << "Display of dequeue element" << endl;

    // Deque display
    for (auto i = s.begin(); i != s.end(); i++)
    {
        cout << d.front() << " ";
        d.pop_back();
    }
    cout << "Deletion of dequeue element" << endl;

    d.pop_back(); 

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Vector-Pair

    // Vector pair initialization 
    vector<pair<int, int>> p;
    
    // Vector pair insertion
    cout << "Insertion in vector pair " << endl;
    cout << endl;

    for (int i = 0; i < n; i++)
    {
        p.push_back({a[i], i});
    }

    // Vector pair display
    cout << "Display of vector pair element" << endl;

    for (auto i = 0; i < v.size(); i++)
    {
        cout << p[i].first << " " << p[i].second << endl;
    }
    cout << endl;
    
    // Vector pair sorting according to first element
    cout << "Sorting according to first element\n";
    sort (v.begin(), v.end());
    cout << "\n";
    
    // Vector pair sorting according to second element
    cout << "Sorting according to second element\n";
    bool second_sorter (const pair <int,int> &a, const pair <int,int> &b) // comparator function, to be put outside main
    {
    	return (a.second < b.second);
    }
    sort (v.begin(), v.end(), second_sorter);
    cout << "\n";

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List

    // List initialization 
    list <int> LI;
    list <int>::iterator it;
    
    // Inserts elements at end of list
    LI.push_back(4);

    // Inserts elements at beginning of list
    LI.push_front(3);

    // Returns reference to first element of list
    it = LI.begin();

    // Inserts 1 before first element of list
    LI.insert(it,1);

    // List traversal
    for(it = LI.begin();it!=LI.end();it++)
    {
        cout<<*it<<" ";
    }
    cout<<endl;

    // Reverse elements of list
    LI.reverse();

    // Removes all occurrences of 5 from list
    LI.remove(5);

    // Removes last element from list
    LI.pop_back();
	
    // Removes first element from list
    LI.pop_front();

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Priority Queue

    // Priority Queue initialization 
	priority_queue<int> pq;

	// Priority queue insertion
	pq.push(10);
	pq.push(20);

	// Priority queue display
	while (!pq.empty()) {
		cout << '\t' << g.top();
		g.pop();
	}
	cout << '\n';
	
	cout << "\n size if pq : " << pq.size();
	cout << "\n top element of pq : " << pq.top();
	
	// Priority queue deletion
	pq.pop();

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