If all of the kids are adept in Logic and Selfish, Allen should propose to give Charlie 2 candybars, Brad 0, Diane 1, and himself 97.
Reasoning:
If Allen's proposal is rejected by 2 of the others, he will be voted out. In this case, you have a group of 3 children where any 2 form a majority. So, the most logical thing to do would be for Brad to give himself 99 and Charlie 1, and Diane 0, seeing as if Charlie rejects the proposal, the group becomes 2 children, and a majority is impossible unless both people agree. Seeing as how Diane, by disagreeing with Charlie, makes herself the majority (enabling herself to get 100 candybars), she will in no way agree with Charlie unless he gives her all 100. Knowing this, Charlie understand that he has no option but to accept Anything Brad would give him (ie, 1 candybar), and if Allen were to offer him 2, this would be better yet. Diane, knowing that if Charlie were to vote in a logical fashion betwixt him and Brad, she would get no candybars from them, and thus has an incentive to accept Allen's offer of 1.
And for the record, the other puzzle is in Chinese, not Japanese.