Re: puzzles, coin weighing, coding

[Pham Thi Thanh Hong <hong@ait.ac.th>]

Hi all, cha`o chi. Ha.nh,

On Wed, 16 Jul 1997, Dao thi Bich Hanh wrote:

> Xin tro+? la.i ba`i toa'n coin weighing. To^i nghi~ la` ne^'u ta
> co' 24 coins trong ddo' co' 1 coin na(.ng ho+n hay nhe. ho+n,
> thi` vo+'i 3 la^`n ca^n, ta va^~n co' the^? xa'c ddi.nh ddu+o+.c
> coin na`o la` coin na(.ng (nhe.) ho+n\. 
> 
> 1.
> Tru+o+'c he^'t, ta xe't tru+o+`ng ho+.p 8 coins vo+'i 2 la^`n ca^n\.
> Chia 8 coins tha`nh 3 nho'm go^`m 3, 3 va` 2 coins. 
> 
> La^`n ca^n thu+' nha^'t :  So sa'nh (ca^n) hai nho'm 3,3 coins. 
>  - Ne^'u hai nho'm na(.ng ba(`ng nhau, the fake coin na(`m trong 
> nho'm go^`m 2 coins co`n la.i, 
>    ne^'u kho^ng, ta xa'c ddi.nh ddu+o+.c nho'm 3 coins na`o chu+'a
> the fake coin va` dda~ quye^'t ddi.nh ddu+o+.c la` no' na(.ng hay
> nhe. ho+n

Chi. Ha.nh tha^n me^'n, em co' ho+i tha('c ma('c cho^~ na`y, ne^'u ta dda~
kho^ng bie^'t the fake coin la` na(.ng ho+n hay nhe. ho+n normal coin thi`
la`m sao co' the^? xa'c ddi.nh ddu+o+.c nho'm 3 coins na`o chu+'a the kafe
coin va` du+.a va`o ca'i gi` dde^? quye^'t ddi.nh la` no' na(.ng ho+n
hay nhe. ho+n normal coin???

Lo+`i gia?i cu?a chi. chi? ddu'ng trong tru+o+`ng ho+.p dda~ cho bie^'t
tru+o+'c the fake coin la` na(.ng ho+n hay nhe. ho+n, trong tru+o+`ng
ho+.p chu+a bie^'t tru+o+'c thi` sao???

Cheers, H