Thanks, I understood now..I have to use already converted char value afterwards also..like if string is "ek" then ( e-> a in 4 moves & k->e in 6 moves & we already have e->a before so we will ignore this so total 10 moves for "ek" to "aa"...)..Thanks :)

Can you please explain the main logic. I mean the lowest possible conversion at that point means what ? Third part I understood that like if suppose 7th char was 's' and we did the calculation for it's conversion then if we get 20th or any further char again 's' then we will simply ignore that since 's' calculation is already done

Can someone please explain how to solve E ? Only thing I figured out was in total at most 26 moves every char in string can be converted to 'a'. So, k>26 will always yields aaa...a which is the smallest lexicographical string ( Correct me if I am wrong )

This missing of atleast almost ruined my contest. I was busy thinking how come it is going wrong on pretest 3 again and again, later realized the mistake.

Hope to become blue this time.