I had a vector of pairs. I wanted it sorted in descending according to the first value of the vector.

sort(a.begin(),a.end(),[](pair<int,int> &left, pair<int,int> &right){
         return left.first >= right.first;
});

This gave me TLE. Sorting it normally

sort(a.begin(),a.end());

and iterating from the end worked.

Why does the first sorting function give TLE? Do I have to implement it some other way?