#include <iostream>

#include <vector>

// Some of the member functions of vectors are:

// at(): Returns the reference to the element at a particular position (can also be done using ‘[ ]’ operator). Its time complexity is O(1).

// back(): Returns the reference to the last element. Its time complexity is O(1).

// begin(): Returns an iterator pointing to the first element of the vector. Its time complexity is O(1).

// clear(): Deletes all the elements from the vector and assign an empty vector. Its time complexity is O(N) where N is the size of the vector.

// empty(): Returns a boolean value, true if the vector is empty and false if the vector is not empty. Its time complexity is O(1).

// end(): Returns an iterator pointing to a position which is next to the last element of the vector. Its time complexity is O(1).

// erase(): Deletes a single element or a range of elements. Its time complexity is O(N + M) where N is the number of the elements erased and M is the number of the elements moved.

// front(): Returns the reference to the first element. Its time complexity is O(1).

// insert(): Inserts new elements into the vector at a particular position. ts time complexity is O(N + M) where N is the number of elements inserted and M is the number of the elements moved .

// pop_back(): Removes the last element from the vector. Its time complexity is O(1).

// push_back(): Inserts a new element at the end of the vector. Its time complexity is O(1).

// resize(): Resizes the vector to the new length which can be less than or greater than the current length. Its time complexity is O(N) where N is the size of the resized vector.

// size(): Returns the number of elements in the vector. Its time complexity is O(1).

using namespace std;

vector<int> a; // empty vector of ints

vector<int> b (5, 10); // five ints with value 10

vector<int> c (b.begin(),b.end()); // iterating through second

vector<int> d (c); // copy of c

void traverse(vector<int> v)

{

vector <int>::iterator it;

for(it = v.begin();it != v.end();++it)

cout << *it << " ";

cout << endl;

for(int i = 0;i < v.size();++i)

cout << v[i] << " " ;

cout << endl;

}

int main()

{

vector <int> v;

vector <int>::iterator it;

v.push_back(5);

while(v.back() > 0)

v.push_back(v.back() - 1);

for(it = v.begin(); it != v.end();++it)

cout << *it << ' ';

cout << endl;

for(int i = 0;i < v.size();++i)

cout << v.at(i) << ' ';

cout << endl;

while(!v.empty())

{

cout << v.back() << ' ';

v.pop_back();

}

cout << endl;

return 0;

}