There is no editorial for this problem, but exists few same solution, for instance: https://www.codechef.com/viewsolution/20215651

This greedy solutions as I see for test:

5 2 3

10 8 4 3 3

will give 13*15 = 195.

But optimal as I see: 14*14 = 196.

Am I right? Does this problem have polynomial solution?