v.push_back( 1 );
v.push_back( 2 );
v.push_back( 3 );

cout << v[0] << " " << v[1] << " " << v[2] << endl; /// 1 2 3

v[1] = 3;
cout << v[0] << " " << v[1] << " " << v[2] << endl; /// 1 3 3

cout << v.size() << endl; /// 3
for ( int i = 0; i < v.size(); i++ ) cout << v[i] << " "; /// 1 3 3
cout << endl;

vector <int> v1 = { 2, 3, 4 };

cout << v1.size() << endl; /// 3
for ( int i = 0; i < v1.size(); i++ ) cout << v1[i] << " "; /// 2 3 4
cout << endl;

v.clear();
cout << v.size() << endl; /// 0
cout << v.empty() << endl; /// 1
cout << v1.empty() << endl; /// 0

v1.resize(5);
cout << v1.size() << endl; /// 5
for ( int i = 0; i < v1.size(); i++ ) cout << v1[i] << " "; /// 2 3 4 0 0
cout << endl;

vector<int> a(5);

cout << a.size() << endl; /// 5
for ( int i = 0; i < a.size(); i++ ) cout << a[i] << " "; /// 0 0 0 0 0
cout << endl;

a = v1;

for ( auto u : a ) cout << u << " "; /// 2 3 4 0 0
cout << endl;

vector<int>::iterator it;
for ( it = a.begin(); it != a.end(); it++ ) cout << *it << " "; /// 2 3 4 0 0
cout << endl;

a = { 3, 4, 5, 1, 2 };

sort ( a.begin(), a.end() ); ///O(n*log2(n))

for ( auto u : a ) cout << u << " "; /// 1 2 3 4 5
cout << endl;

sort ( a.rbegin(), a.rend() );

for ( auto u : a ) cout << u << " "; /// 5 4 3 2 1
cout << endl;


a = { 3, 4, 5, 1, 2 };
sort ( a.begin(), a.end(), greater<int>() );

for ( auto u : a ) cout << u << " "; /// 5 4 3 2 1
cout << endl;

a = { 3, 4, 5, 1, 2 };

reverse( a.begin(), a.end() );

for ( auto u : a ) cout << u << " "; /// 2 1 5 4 3
cout << endl;

cout << a.back() << endl; /// 3
a.pop_back(); /// O(1) complexity.
cout << a.back() << endl; /// 4


a = { 3, 4, 5, 1, 2 };
cout << *a.begin() << endl; /// 3

a.erase( a.begin() ); /// O(n) complexity.
for ( auto u : a ) cout << u << " "; /// 4 5 1 2
cout << endl;

a.erase( a.begin()+2 );
for ( auto u : a ) cout << u << " "; /// 4 5 2
cout << endl;

a = { 1, 1, 2, 2, 2, 3, 3 };
unique( a.begin(), a.end() );

for ( auto u : a ) cout << u << " "; /// 1 2 3 2 2 3 3
cout << endl;


a = { 1, 1, 2, 2, 2, 3, 3 };
int n = unique( a.begin(), a.end() ) - a.begin();

cout << n << endl; /// 3
for ( int i = 0; i < n; i++ ) cout << a[i] << " "; /// 1 2 3
cout << endl;

a = { 2, 3, 1, 5 };
cout << max_element( a.begin(), a.end() ) - a.begin() << endl; /// 3
cout << *max_element( a.begin(), a.end() ) << endl; /// 5

return 0;
}