Problem 1: Alien Game

Aliens on the Unknown planet have a tradition of playing a game called Loiten. It is played by two players who alternate turns. There are N buckets with apples standing in one line in front of the players. They are numbered from left to right with integers starting from 1. In one turn a player can select one of the buckets, which is not the first and not the last and has a positive number of apples in it, and move all of that bucket’s apples to the bucket adjacent to the left and at the same time move all of them to the bucket adjacent to the right. That’s right, the number of apples can be negative as it is a really strange planet. Thus, if there are 3 consecutive buckets with the number of apples being x, y, z, then you can perform the move if y is greater than zero. The resulting capacity of the buckets will be as follows: x+y, – y, z+y. The first player who can’t make a move loses. You happen to know one of the aliens from the Unknown planet, named Popo. He is a very good Loiten player, and has reached the Loiten Finals. On the day prior to the game, he found out the number of apples in each of the buckets. Unfortunately, his memory is not that good, and he can’t remember the number of apples in the P-th bucket. He just remembers that it is a number with absolute value not greater than F. Now, he is asking you to help him to calculate his chances. The players at the Finals are so good that they only make optimal moves to maximize their chance of winning. If neither player can win, the game is considered a draw. You are to find the number of possible apple counts for the bucket with an unknown number of apples where Popo will win. Popo is also sure that he is the one to make the first turn.

2017-10-21