99 for himself, 0 for 4-th, 0 for 3rd, 1 for 2-nd and 0 for youngest - here is why
I agree to 3 pirates situation - if it comes to that, split 99 - 1- 0 and game is over, youngest gets 0, second youngest gets none - the 2 pirates situation will never happen.
So in situation 4 pirates the fourth splits 99 : 0 : 1 : 0 (both youngest will never get a better deal so they will vote yes (remember they are reasonable- death of fourth won't give them better deal.
The same apply to 5 pirates voting : 99 : 0 : 0 : 1 : 0 - the oldest will get votes of both youngest ones