Deque in STL C++
About Deque in STL :
Deque in STL is defined as the container used to insert and remove elements at both ends. They are implementing using queue data structure.
Introduction to Deque in C++
Deque, short for “Double-Ended Queue,” is an essential data structure in C++ provided by the Standard Template Library (STL). It shares similarities with vectors and lists but offers additional benefits due to its versatile nature. A Deque allows elements to be inserted or removed from both ends efficiently, making it an excellent choice for various applications.
Advantages of using Deque:
Dynamic Size: Unlike arrays, Deque can change its size dynamically, making it more flexible in handling varying amounts of data.
Fast Insertions and Deletions: Deque enables fast insertions and deletions at both ends, providing efficient data manipulation.
Random Access: Like vectors, Deque allows for direct access to elements using indexing, ensuring quick element retrieval.
Memory Efficiency: Deque optimizes memory utilization, making it an ideal choice for large-scale applications.
Functions in Deque :
| Function | Working |
|---|---|
| push_back() | insert an element to the back end of the deque. |
| push_front() | insert an element to the front end of the deque. |
| size() | give the number of elements present in the deque. |
| empty() | tells whether the deque is empty or not. |
| max_size() | return the maximum number of elements can deque hold. |
Basic Operations on Deque
Initializing a Deque:
To use a Deque, we need to include the header file in our C++ program. We can then create a Deque object using its constructor.#include < iostream >
#include < deque >
int main() {
std::deque<int> myDeque; // Initializing an empty integer Deque
return 0;
}
Insertion and Deletion of Elements:
Deque supports several methods for inserting and removing elements. Some commonly used functions include push_back(), push_front(), pop_back(), and pop_front(). Insertion and Deletion of Elements:#include <iostream>
#include <deque>
int main() {
std::dequemyDeque;
myDeque.push_back(10); // Insert 10 at the end
myDeque.push_front(5); // Insert 5 at the beginning
myDeque.pop_back(); // Remove the last element
myDeque.pop_front(); // Remove the first element
return 0;
}
Accessing Elements in Deque:
Elements in a Deque can be accessed using the subscript operator [] or the at() function.
#include <iostream>
#include <deque>
int main() {
std::deque<int>myDeque;
myDeque.push_back(10);
myDeque.push_back(20);
myDeque.push_back(30);
int elementAtIndex1 = myDeque[1]; // Access the element at index 1 (20)
int elementAtIndex2 = myDeque.at(2); // Access the element at index 2 (30)
return 0;
}
Implementation of Deque in STL
The C++ Standard Template Library (STL) provides a rich set of classes and functions to work with data structures like Deque.
Code example of Deque implementation:
#include <iostream>
#include <deque>
int main() {
std::deque<int>myDeque;
myDeque.push_back(10);
myDeque.push_back(20);
myDeque.push_front(5);
std::cout << "Front element: " << myDeque.front() << std::endl; // Output: Front element: 5
std::cout << "Back element: " << myDeque.back() << std::endl; // Output: Back element: 20
return 0;
}Use Cases of Deque in C++
Deque finds applications in various scenarios due to its unique characteristics. Real-world scenarios for Deque:
Task Scheduling: Deque can be used in task scheduling algorithms, where new tasks can be added or removed efficiently from both ends.
Sliding Window Technique: Deque is commonly used to solve problems involving sliding window algorithms, where elements move in a fixed-size window.
Undo/Redo Operations: Deque’s ability to insert and remove elements from both ends makes it suitable for implementing undo and redo functionalities in applications.
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