Albert and Bernard just become friends with Cheryl, and they want to know when her birthday is. Cheryl gives them a list of 10 possible dates.
May 15, May 16, May 19,
June 17, June 18,
July 14, July 16,
August 14, August 15, August 17
Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively.
Albert: I don't know when Cheryl's birthday is, but I know that Bernard does not know too.
Bernard: At first I don't know when Cheryl's birthday is, but I know now.
Albert: Then I also know when Cheryl's birthday is.
So when is Cheryl's birthday?
這是新加坡一題中學生數學考題，需要靠邏輯推理解題，大家想想看。
蛇年獻禮：貪吃蛇大戰
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貪吃蛇大戰是由游龍棋改編的二人遊戲，每方控制一條蛇，目標是將隨機産生的食物吃掉，同時蛇會加長。最後比誰的蛇最長。
本遊戲是同步行棋，即雙方同時行動。由於每次行動都只有兩種選擇，因此不會産生共點問題。當兩隻蛇頭不可避免相撞時，遊戲結束。 規則說明 未完待續
13 小時前
July16
回覆刪除第一句排除5、6月
第二句排除14、18、19號
第一輪交談過後，算算只剩下7.16，8.15，8.17三天
第三句過後，結果是二人皆知，故排除8月，因其有兩天，如只知道月份則不能確定是哪天。
（這題有不少變式，有些還加上了文字遊戲，很有意思。）
正解，這題目推理有其難度，能答得出來不簡單。
回覆刪除第三句可以改成：But I still don't know.
回覆刪除第四句：You should know that later.
第五句：Thanks, you are very kind.
嗯，這個改編不錯，讓我記下來
刪除Albert: But I still don't know.
Bernard: You should know that later.
Albert: Thanks, you are very kind.