STL

Question 1

Size of vector

Answer 1

v.size()

Question 2

Is vector empty

Answer 2

v.empty()

Question 3

Vector of 10 vectors

Answer 3

vector< int > v[10];

Question 4

Vector of size 10

Answer 4

vector< int > v(10);

Question 5

Add new element to the vector

Answer 5

v.push_back(i);

Question 6

Clear vector

Answer 6

v.clear()

Question 7

Vector of 20 strings

Answer 7

vector< string > v(20, “Unknown”);

Question 8

N*M matrix filled with -1

Answer 8

vector< vector< int > > Matrix(N, vector< int >(M, -1));

Question 9

Pass vector to function

Answer 9

void function(vector< int > &v);

Question 10

Declare stack

Answer 10

stack< int > s;

Question 11

Push to stack

Answer 11

s.push(i)

Question 12

Pop from stack

Answer 12

s.pop()

Question 13

Top of the stack

Answer 13

s.top()

Question 14

Is stack empty

Answer 14

s.empty()

Question 15

Size of stack

Answer 15

s.size()

Question 16

Pair is defined in which header?

Question 17

Access pair elemetns

Answer 17

P.first; P.second

Question 18

c.end() points to —- ?

Answer 18

The first invalid object right after the last element

Question 19

c.begin == c.end means?

Answer 19

c.empty() is true

Question 20

c.end() - c.begin() = ?

Answer 20

c.size()

Question 21

reverse() and sort() take — as parameters

Answer 21

container pointers eg. c.begin() or c.end()

Question 22

Find 49 in and array(or vector)

Answer 22

find(v.begin(), v.end(), 49) != v.end()

Question 23

Useful macro for all elements of container

Answer 23

define all(c) c.begin(), c.end()

Question 24

sort in reverse order

Answer 24

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

Question 25

traverse container beginning to end

Answer 25

#define tr(c, it) \
for(typeof(c.begin()) it = c.begin(), it != c.end(); it++)

Question 26

Insert 42 in a vector at index 1

Answer 26

v.insert(1, 42);

Question 27

Insert a new vector at index 1

Answer 27

v.insert(1, all(v2))

Question 28

erase an element from vector

Answer 28

v.erase(iterator) NOT v.erase(index)

Question 29

erase a range from vector

Answer 29

v.erase(begin iterator, end iterator)

Question 30

substring

Answer 30

s.substr(0, s.length() - 1)

Question 31

declare a set

Answer 31

set< int > s;

Question 32

add to set

Answer 32

s.insert(i);

Question 33

erase from set

Answer 33

s.erase(i);

Question 34

find element in a set

Answer 34

s.find(42); s.find(i);

Question 35

macro is container present

Answer 35

define present(c, e) c.find(e) != c.end()

Question 36

get rid of duplicates in a vector

Answer 36

set< int > s(all(v));

Question 37

declare a map

Answer 37

map< string, int > m;

Question 38

access a map

Answer 38

m[“top”], m[“coder”];

Question 39

add element to map

Answer 39

m.insert(pair< string, int > (“top”, 1);

Question 40

assign value to map

Answer 40

m[“top”] = 1

Question 41

Use this when traversing map

Answer 41

tr(c, it) {
it->second;
}