ABC059D Alice & Brown
In this game, there are two piles initially consisting of $X$ and $Y$ stones, respectively. Alice and Brown alternately perform the following operation, starting from Alice:
Take $2i$ stones from one of the piles. Then, throw away $i$ of them, and put the remaining $i$ in the other pile. Here, the integer $i$ ($1\le i$) can be freely chosen as long as there is a sufficient number of stones in the pile. The player who becomes unable to perform the operation, loses the game.
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原文：https://www.cnblogs.com/Patt/p/12147549.html