Sorting an array according to another array using pair in STL

We are given two arrays. We need to sort one array according to another.

Examples:

Input : 2 1 5 4 9 3 6 7 10 8
        A B C D E F G H I J

Output : 1 2 3 4 5 6 7 8 9 10 
         B A F D C G H J E I 
Here we are sorting second array
(a character array) according to 
the first array (an integer array).

We have discussed different ways in below post.
Sort an array according to the order defined by another array



In this post we are focusing on using the pair container present in STL of C++.

To achieve our task we are going to make pairs of respective elements from both the arrays.Then simply use the sort function. The important thing to note is, the first element in the pairs should be from the array according to which the sorting is to be performed.

filter_none

edit
close

play_arrow

link
brightness_4
code

// Sort an array according to 
// other using pair in STL.
#include <bits/stdc++.h>
using namespace std;
  
// Function to sort character array b[]
// according to the order defined by a[]
void pairsort(int a[], char b[], int n)
{
    pair<int, char> pairt[n];
  
    // Storing the respective array
    // elements in pairs.
    for (int i = 0; i < n; i++) 
    {
        pairt[i].first = a[i];
        pairt[i].second = b[i];
    }
  
    // Sorting the pair array.
    sort(pairt, pairt + n);
      
    // Modifying original arrays
    for (int i = 0; i < n; i++) 
    {
        a[i] = pairt[i].first;
        b[i] = pairt[i].second;
    }
}
  
// Driver function
int main()
{
    int a[] = {2, 1, 5, 4, 9, 3, 6, 7, 10, 8};
    char b[] = {'A', 'B', 'C', 'D', 'E', 'F'
                         'G', 'H', 'I', 'J'};
                           
    int n = sizeof(a) / sizeof(a[0]);
      
    // Function calling
    pairsort(a, b, n);
  
    for (int i = 0; i < n; i++)
        cout << a[i] << " ";
    cout << endl;
  
    for (int i = 0; i < n; i++)
        cout << b[i] << " ";
          
    return 0;
}

chevron_right


Output:

1 2 3 4 5 6 7 8 9 10 
B A F D C G H J E I 

This article is contributed by Vineet Joshi. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.



My Personal Notes arrow_drop_up

Improved By : cs_abhi



Article Tags :
Practice Tags :


1


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.