RE: [REBOL] Re: A Rebol Challenge. The Monty Hall Puzzle
[EMAIL PROTECTED] wrote: > > On 17-Dec-01, Carl Read wrote: > > > Here's a fixed version... > > > rebol[]k: s: 0 r: func[n][random n]m: does[p: r 3 c: r 3 p = c] loop > > 10000 [if m[k: k + 1]if not m[s: s + 1]]print ["Kept" k "Switched" > > s] > > > Nowhere near as short as some of the other posts, but anyway, here's > > my reasoning behind it... > > > The prize is placed behind one of 3 doors... > > > prize: random 3 > > > You choose one of the doors... > > > chosen: random 3 > > > Now, Monty can see if they're a match - ie, if you've picked a > > winner... > > > matched?: prize = chosen > > > Which returns true if you've chosen the prize. If you decide to keep > > this then it's obvious (I hope:) that you had 1 chance in 3 of > > picking the prize. > > > But what if you accept Monty's offer to switch? Well, there's only > > two posibilities: > > > 1) You'd chosen the prize, so switching from that means you lose > > regardless of what Monty does. > > > 2) You hadn't chosen the prize, Monty exposes the other losing door, > > and so you switch to the winning door. > > > So a switch always means a reversal of your original choice - a > > winning choice becoming a losing one and vice-versa. So... > > > matched?: not matched? > > > But what happens to the "1 chance in 3 of picking the prize."? Well > > that also means you had 2 chances in 3 of losing, right? And the > > switch makes an original loss a win, so switching gives you 2 > > chances in 3 of winning, thus doubling your chances of a win. > > After showing the above explaination to someone (not on this list) > they still didn't believe it, so I've written a graphical version in > the hope that pictures will win out where words fail... (Not a View > version though - run it from the Console.) > well, thats to complicated to me, i give up. i have a 2/3 choice to get a priceless door, this chances are better, and so i want to be priceless. hey, and if i hit, Monty will show me the other priceless door! so i have two :) happy without a price -Volker ;-) > > rebol [] > doors: func [n c][ > d: copy/deep ["[ ]" "[ ]" "[ ]"] > d/:n/2: c > return d > ] > game: does [ > print " Switching Keeping" > prize: random 3 > print ["Prize: " doors prize #"P" " " doors prize #"P"] > guess: random 3 > print ["Guess: " doors guess #"G" " " doors guess #"G"] > opened: first random difference [1 2 3] reduce [prize guess] > prin ["Opened:" doors opened #"X"] > prin " " > print either prize = guess [kept: kept + 1 "Win"]["Loss"] > sw: first difference [1 2 3] reduce [guess opened] > print ["Switch:" doors sw #"S"] > prin " " > print either prize = sw [switched: switched + 1 "Win"]["Loss"] > > played: played + 1 > print [ > "Wins: " switched " " > kept > " Played:" played > ] > ] > played: 0 > kept: 0 > switched: 0 > quit?: false > print "" > while [not quit?][ > game > print "" > print "Enter to continue - Esc to quit." > > inp: input > quit?: inp = "q" > ] > > > Enough! (: > > -- > Carl Read > > -- > To unsubscribe from this list, please send an email to > [EMAIL PROTECTED] with "unsubscribe" in the > subject, without the quotes. > -- To unsubscribe from this list, please send an email to [EMAIL PROTECTED] with "unsubscribe" in the subject, without the quotes.
