STL Data Structures
Learn about basic STL data structures
Vector
A vector is a dynamic array. It works like a normal array, but it can grow and shrink automatically.
Basic operations:
- Declare:
vector<int> vorvector<int> v(n)orvector<int> v(n, value) - Size:
v.size() - Access:
v[i] - Add to end:
v.push_back(x) - Remove last:
v.pop_back() - Last element:
v.back() - Check if empty:
v.empty() - Clear all:
v.clear()
Example: reading numbers and printing them in reverse:
Queue
A queue is a First In First Out (FIFO) structure. The first element added is the first element removed, like a line of people.
Basic operations:
- Declare:
queue<int> q - Add element to the end:
q.push(x) - Remove element from the front:
q.pop() - Access front element:
q.front() - Access last element:
q.back() - Check if empty:
q.empty() - Size:
q.size()
Example: process tasks in the order they arrive.
Deque
A deque (double ended queue) allows pushing and popping from both front and back in time. It combines some features of both queue and vector.
Basic operations:
- Declare:
deque<int> d - Add to front:
d.push_front(x) - Add to back:
d.push_back(x) - Remove from front:
d.pop_front() - Remove from back:
d.pop_back()