about me



Yucatán Photos

St Lucia Photos

Photo Album



< July 2010 >
     1 2 3
4 5 6 7 8 910

past articles »

Click for San Francisco, California Forecast

San Francisco, USA


Find Sophie Solution (Facebook Programming Puzzle)

This is the fourth and probably my last post about solving Facebook programming puzzle. The Find Sophie problem is a buffet (hardest) level puzzle. It is basically a variation of the traveling salesman problem. Traveling salesman is of course, a NP-complete problem. But before you throw up your hand, consider the puzzle refers to locations in your home where you may find a cat. Just how many locations are there. Let's say living room, dining room, bedroom, on the bed, under the desk, behind the curtain, ... etc. If Facebook is not very wicked, this puzzle should be bounded to a low hundreds of locations. This mean it is still possible to solve using some relatively simple search algorithm.

Here is the outline of my solution:

  1. Prepare to enumerate all paths.
  2. Prefer the local optimal during the search. Remember the best solution encountered so far.
  3. Prune the search tree. For example if the current best solution has a score of 50. When you are considering another path, as soon as its score exceed 50, you should abandon it.
  4. Improve the pruning by taking the additional score to complete the path into account. For example, if the current score of a partial path is S, the minimum score to complete the remaining walk is Rmin. Then if S+Rmin > best score, prune it.

Actually I have submitted the solution a few months ago. Only today do I find out I have not posted my solution in my blog. So I'm really speaking from my memory. I hope my plan is still accurate. Again my un-tidied code is available.

The other 3 facebook puzzles I have solved was posted below:

2010.07.22 [] - comments



blog comments powered by Disqus

past articles »


BBC News


Zika virus: Florida cases 'highly likely' to be first US-based infections (29 Jul 2016)


Syria conflict: Deadly strike on Save the Children maternity hospital (29 Jul 2016)


France church attack: Manuel Valls highlights 'justice failure' (29 Jul 2016)


Sweden to investigate sex lives (29 Jul 2016)


US election: US faces 'moment of reckoning' says Hillary Clinton (29 Jul 2016)


San Diego policeman shot dead (29 Jul 2016)


India Dalit couple hacked to death over 22 cents debt (29 Jul 2016)


Petition demands apology for Chinese lesbian couple denied diploma (29 Jul 2016)


Hissene Habre: Chad's ex-ruler ordered to pay compensation to victims (29 Jul 2016)


Amazon's Bezos world's third-richest person (29 Jul 2016)

more »


SF Gate


Bay Area News (7 Jan 2012)


City Insider (11 Feb 2012)


Crime Scene (13 Feb 2012)


C.W Newius Column (10 Jan 2012)


C.W. Nevius Blog (11 Feb 2012)


Education News (10 Jan 2012)


KALW (11 Feb 2012)


Matier and Ross Blog (11 Feb 2012)


Scrutiny for all-cash home sales; Facebook birthday videos (28 Jul 2016)


Business News Roundup, July 29 (28 Jul 2016)


US homeownership rate of 62.9 percent matches a 51-year low (28 Jul 2016)


Alphabet earnings soar despite rising ‘moonshot’ losses (28 Jul 2016)


To reverse damage of sitting, take a brisk, hour-long walk (28 Jul 2016)


Peek, SF tourism startup, raises million from investors (28 Jul 2016)

more »


Site feed Updated: 2016-Jul-29 09:00