In C++, map containers allow us to store the data in key-value pairs. There might be some cases where you want to convert an entire map into a vector of pairs. In this article, we will learn how to convert a map into a vector of pairs.

Example

Input: map<int,string>mp ={ {1,"one"}, {2,"two"}, {3,"three"}}
Output: vector<pair<int,string>>vec= { (1,"one"), (2,"two"), (3,"three")}
Input: map<int,char>mp ={ {1,'a}, {2,'b'}, {3,'c'}}
Output: vector<pair<int,char>>vec= {(1, 'a'), (2, 'b'), (3, 'c')}

Convert Map to a Vector of Pairs

To convert a map to a vector of pairs, we can use the std::copy method provided by the C++ Standard Template Library (STL) to copy the elements from the map to a vector of pairs. We can use the back_inserter() function to make sure that the elements are inserted at the end of the vector.

C++ Program to Convert Map to Vector of Pairs Using std::copy Method

Vector Elements:
(1, a ) 
(2, b ) 
(3, c ) 

Time complexity: O(N), to traverse the whole map and copy values to vector using the copy method.
Auxilary Space: O(1), as no extra space is used for conversion.