Question

In C++ please.

4. Differentiate sequential, associative and unordered STL containers. Explain the need for specialized list algorithms, i.e. why it is not sufficient to use general purpose STL algorithms. Give an example use of one such algorithm.

Answer 1

Sequential Container :

Sequential containers are those data structures that store data sequentially, hence elements are accessed sequentially.

These are some sequential container like

1. ARRAY: It is used to stores data of the same types like ar[int], arr[char]... It has a fixed size.

2. VECTOR: It can grow dynamically(size can grow automatically as elements increase ) and fast random access are also there.

3. dequeue : It is doubly ended queue and supports insertion and deletion from front and back both side. as well as fast random access is also there.

4. List : it is a doubly-linked list library in c++. Doubly linked list provides the functionality of deletion and insertion faster in O(1) time.

Associative Container : These types of containers like map , set , multimap , multiset.

1.map : It contains that data in key - value pair and key must be unique and ordered map supports accessing element in O(long) and allow accessing of elements in constant time in O(log n) time .

2. set : set contains all the unique elements and supports insert in o(n) but searching is fast in O(log n).

3. multiset : Same as set but here duplicate elements can be also there.

4 .multimap: it is same as map but key need not to be unique

NOTE : most of the insertion and deletion and searching in associative containers have time complexity of O(log n)

unordered STL containers : These containers are like unordered_map, unordered_set, unordered_multiset ,unordered_multimap.

General purpose STL algorithms are not sufficient because we can have to do modification under some of the code to implement some new things , but in stl they are pre-implemented so we can only use it is difficult to modify the STL library.

eg. of deueue of stl

#include<bits/stdc++.h>
using namespace std;  

int main()
{
   deque<int>dq; // define doubly ended queue from STL directly
   dq.push_back(1); // to push element in back of queue
   dq.push_back(2); // to push front of queue
   dq.pop_front(); // to pop element from front
   dq.push_front(5); // to push front of queue
   dq.push_back(8); // to push element in back of queue

for(int x:dq)
cout<<x<<" ";

   return 0;
}

Output: 5 2 8