Sunday, 31 July 2005



早到了就在老麥等,睇下新聞睇下XBOX NEWS。好期望360到來,基本上一出我就會買,三千蚊,豪俾佢啦。希望可以慳到位,加上有無線,很好。舊機,真可惜,係衰大份。


更期望是GBM Gameboy Micro,快D出啦。到時會換掉部GBA SP吧。

Saturday, 30 July 2005

Warranty Service

I want to send my old 120 GB harddisk back for service, before its 3 years warranty expired. For over one and a half years the harddisk was not working well. It will roars when spinning. That's scary.

I just registered at Hitachi's website. Now I've to send it back via mail. The troublesome job is to find some thick foam to wrap the harddisk. Netiher bubble wrap nor styrofoam peanuts is allowed. Otherwise, warranty will be voided immediately. The harddisk only worth just $300 but the cost of shipment and handling make it not worth the price. (see Hitachi Packaging instructions)

It might be easier for me to just throw it away rather than having it fixed. Sigh.

coin weighting problem

coin weighting (ref:

you have 12 coins. one of them is counterfeit. all the good coins weight the same, while the counterfeit one weights either more or less than a good coin.

your task is to find the counterfeit coin using a balance-scale in 3 weights. moreover, you want to say whether the coin weighs more or less than is should and, and this is the real kicker, your weighs must be non-adaptive.

that is, your choice of what to put on the balance for your second weigh cannot depend on the outcome of the first weigh and your decision about what to weigh for round 3 cannot depend on what happened on either your first or second weigh.

for example, you can't say something like "take coin #1 and coin #2 and weigh them. if they balance, then take coins 3,4,5 and weight them against 6,7,8...if 1 and 2 don't balance, then weigh #1 vs #2..." you have to say something like:

round #1: do this
round #2: do this
round #3: do this

if the results are left tilt, balanced, and right tilt, respectively, then coin #11 is heavier than it should be.

this problem is took me about 1-2 hours of working on it to get it. i think even finding the counterfeit using an adaptive solution is tough. then non-adaptive constraint makes it quite hard and having to find whether it's heavier and lighter is cruel and unusual riddling ;-)

have fun...

Since the official website does not have a solution (not a sound solution), so I posted my solution online.

Friday, 29 July 2005






weighting problem: classical

Classic Weighting (ref:

Problem: The evil king from before sends his own assassin to take care of the evil queen who tried to poison him. Of course, her trusty guards catch the assassin before any harm is done. The queen notices that the assassin is quite handsome and doesn't really want to punish him by death. She decides to test his wisdom.

The queen gives the assassin 12 pills which are all completely identical in shape, smell, texture, size, except 1 pill has a different weight. The queen gives the man a balance and tells him that all the pills are deadly poison except for the pill of a different weight. The assassin can make three weighings and then must swallow the pill of his choice. If he lives, he will be sent back to the bad king's kingdom. If he dies, well, thats what you get for being an assassin.

Only one pill is not poison and it is the pill which has a different weight. The assassin does not know if it weighs more or less than the other pills. how can he save his skin?

Official solution

An easier version of this question is that you knew the non-poison bill is heavier (or lighter, similiar logic apply).

Tuesday, 26 July 2005


經典的街機泡泡龍 ,去到第十四關了。努力中~


Friday, 22 July 2005



HP Scanjet 5550C
像數唔知,速度唔知,不過對它的APF(Auto Paper Feeder)很有興趣,能將一疊紙即時變成pdf。若唸大學時有佢就「正」,可以高速分享筆記。

HP Photostyle Scanner 1200
1200 dpi,有SD/CF card reader,比PS2 Slim版大少少,放四粒AA電就可以「處處SCAN」,周圍SCAN人地D相,不過速度就認真麻麻。不過只賣一百塊,仲想點?