what is the most efficient way to achieve this kind of sorting?



Given an array A[0…N] I want a key value pair store which is in descending order of occurrences of element.i.e, The most occurring element appears first then second most occurring and so on.


I am waiting for someone to actually reply and giving answer to your encounters as well. pray hard


Here is O(nlogn) solution if you are looking for better than this I am sorry.

Just use std::pair with p.first = element and p.second = occurrence than you can use the sort function like this
where n = number of elements and cmf is the comparison function you have to define.

int cmf (pair < int , int > p1 , pair < int , int > p2)


return 1;


return 0;



You can’t do it better than Omega(n log n) by any comparison sort including the builtin methods.


Refer to the 1st answer of this link it has been explained