🪨 取石子Nim
在线取石子（尼姆游戏）：桌上有几堆石子，你和电脑轮流从任意一堆里拿走任意多个（至少 1 个）。普通模式拿到最后一个石子的人赢，反常模式拿到最后一个的人输。可选 3～5 堆、谁先手和电脑难度，困难模式的电脑会用异或必胜策略，看看你能不能找到破解方法。Nim online: there are several rows of stones and you and the computer take turns removing any number (at least one) from a single row. In normal play whoever takes the last stone wins; in misère play the last stone loses. Choose 3 to 5 rows, who goes first and the difficulty — the hard computer plays the perfect XOR strategy, so can you beat it?
点一个石子，会选中它和它右边的所有石子，再点“拿走”（或再点一次同一个石子、按回车）确认。Tap a stone to select it and every stone to its right, then press Take (or tap the same stone again, or press Enter).
玩法说明与常见问题How to play & FAQ
「取石子」怎么玩？How do I play Nim?
每回合只能从一堆里拿，至少拿 1 个，最多可以把整堆拿完。取胜的秘诀是“异或”：把每堆石子数写成二进制，按位异或，如果结果为 0，当前要走的一方就处在必败局面。所以你每次都要设法拿完后让各堆的异或值变成 0。反常模式几乎一样，只是在只剩一些 1 个石子的堆时要反过来考虑。Each turn you take from one row only — at least one stone, up to the whole row. The secret is XOR: write each row's count in binary and XOR them together; if the result is 0, the player about to move is losing. So always leave the XOR at 0 after your move. Misère play works the same way until only rows of one stone remain, when you flip the goal.
先手一定能赢吗？Does the first player always win?
不一定。如果开局各堆的异或值是 0，先手方在对手不失误的情况下必输；否则先手方有必胜走法。No. If the rows XOR to 0 at the start, the first player loses against perfect play; otherwise the first player has a winning move.
取石子靠运气吗？Is Nim a game of luck?
完全不靠运气。取石子是经典的数学策略游戏，除了开局堆数随机，每一步都由双方自己决定，纯属锻炼思维的娱乐。Not at all. Nim is a classic mathematical strategy game — apart from the random starting rows, every move is a choice, and it's purely a brain teaser.
「取石子」免费吗？需要下载吗？Is Nim free? Do I need to download anything?
完全免费，无需注册、下载或安装，打开网页就能玩，手机、平板和电脑都支持；游戏完全在你的浏览器本地运行，不会上传任何数据。It is completely free with no sign-up, download or install — just open the page on a phone, tablet or computer. The game runs entirely in your browser and nothing is uploaded.