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pithecanthropus

Death Wish

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One Hundred Copper Coins

In Rengefall, copper coins are minted with the portrait of the Queen on one side and the portrait of the King on the other side.

On this day, the half-crazed executioner gives the captured Talin one chance to avoid execution. The executioner brings Talin into an unlit room. He tells Talin that scattered on the table in front of him are one hundred copper coins of which twenty have the Queen side facing up while the rest have the King side facing up. If Talin can separate the coins into two piles, each with the same number of Queens facing up, he will release Talin. One other constraint is that Talin must accomplish this task in 5 minutes. If Talin fails, he will be beheaded.

It is impossible for Talin to see which side the coins are facing up in the darkness, and the contours of the portraits are too similar to decipher by touch. Nevertheless, Talin managed to separate the coins into two piles with the same number of Queens facing up in the time allotted. How did he accomplish this?

(The correct answer does not involve standing coins on their edges. Elegant logic puzzles do not involve semantic loopholes.)

nickyee.com

Edited by koutei

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Talin mengambil 20 koin secara acak, dan membalik mereka semua. (jadi yang semula King jadi Queen dan Queen jadi King) Lalu ia mengumpulkan 20 koin tersebut dalam satu tumpukan dan 80 koin sisanya dalam tumpukan yang satunya.


Bukti: Misalkan koin Queen yang terambil Talin pada 20 koin tersebut sebanyak q, dan koin King sebanyak 20 - q. ini berarti ada 20 - q koin Queen di tumpukan 80 koin sisa. Namun, setelah pembalikan, tumpukan pertama menjadi 20 - q koin Queen dan q koin King. Artinya tumpukan pertama dan kedua mempunyai jumlah koin Queen yang sama.



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Talin mengambil 20 koin secara acak, dan membalik mereka semua. (jadi yang semula King jadi Queen dan Queen jadi King) Lalu ia mengumpulkan 20 koin tersebut dalam satu tumpukan dan 80 koin sisanya dalam tumpukan yang satunya.

Bukti: Misalkan koin Queen yang terambil Talin pada 20 koin tersebut sebanyak q, dan koin King sebanyak 20 - q. ini berarti ada 20 - q koin Queen di tumpukan 80 koin sisa. Namun, setelah pembalikan, tumpukan pertama menjadi 20 - q koin Queen dan q koin King. Artinya tumpukan pertama dan kedua mempunyai jumlah koin Queen yang sama.

 

bagaimana kalau dua piles nya harus berisi masing-masing 50 koin?

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