Bouns Questions

1. Write code to iterate from the first element to the last element when the vector is given

void iter(vector<int> v)
{
    vector<int>::iterator it1,it2;
    
    for(it1=v.begin(),it2=v.end(),it2;it1!=it2;it1++)
    {
        cout<<*it1<<" ";
    }   
    
    cout<<endl;
}

 2. Write code to sort and reverse the vector.

vector<int> sortVector(vector<int> v)
{
    sort(v.begin(), v.end());
    return v;
}

vector<int> reverseVector(vector<int> v)
{
    for(int i = 0, j = v.size() - 1; i < j; i++, j--)
        swap(v[i],v[j]);

    return v;
}

4. Declare, Insert and Print a pair of strings paired with another pair of int paired with int.

//Declaration of Pair
pair<string,pair<int,int>> x;

//Inserting element
x= { "Geeks" , { 1, 2} };

//Printing element
cout<<x.first<<" "<<x.second.first<<" "<<x.second.second;

5. Find the index of a given element in a vector, such that the next element to it is 2, and if there exists more than one such index returns the larger one if there is no such index then return -1.

int find_index(vector<int> &V,int a)
{
    stack<int> temp;
    
    for(int i=0;i<V.size();i++)
    {
        if(V[i]==a){
            temp.push(i);
        }
        
        if(i==temp.top()+1){
            if(V[i]==2)
                continue;
            else if(V[i]==a){
                temp.pop();
                temp.push(i);
            }
            else{
                temp.pop();
            }
        }
    }
    
    if(temp.top()==V.size()-1)
        temp.pop();

    if(temp.size()==0)
        return -1;
        
    return temp.top();
}

6. Write a Class stack to implement a stack using a queue.

class Stack {
    queue<int> q1, q2;
 
public:
    void push(int x)
    {
        q2.push(x);
        
        while (!q1.empty()) {
            q2.push(q1.front());
            q1.pop();
        }
 
        queue<int> q = q1;
        q1 = q2;
        q2 = q;
    }
 
    void pop()
    {
        if (q1.empty())
            return;
        q1.pop();
    }
 
    int top()
    {
        if (q1.empty())
            return -1;
        return q1.front();
    }
 
    int size()
    {
        return q1.size();
    }
};

7. Write a code to perform push from the back, pop from the front, get the size, get back and get front operations.

void push(queue<int> &q,int x)
{
    q.push_back(x);
}

int pop(queue<int> &q)
{
    int x=getFront(q);
    q.pop_front();
    
    return x;
}


int getSize(queue<int> &q)
{
    return q.size();
}

int getBack(queue<int> &q)
{
    return q.back();
}

int getFront(queue<int> &q)
{
    return q.front();
}

8. Write a code to check duplicate values in the vector and print them with the best possible time complexity.

void dupicate(vector<int> &V)
{
    unordered_set<int> store;
    
    for(auto it:V)
    {
        if(store.find(it)!=store.end())
        {
            cout<<it<<" ";
        }
        else
        {
            store.insert(it);
        }
    }
}

The Standard Template Library (STL) is a set of C++ template classes that are used to implement widely popular algorithms and data structures such as vectors, lists, stacks, and queues. It is part of the C++ Language ISO standard. STL is a popular topic among interviewers, so it is useful for both freshers and experienced to learn the commonly asked interview question on STL in C++.

In this article, we will see the top 50 most important and most frequently asked interview questions on C++ STL.