[Haskell-cafe] Haskell, Microsoft, and interview questions
Richard A. O'Keefe
ok at cs.otago.ac.nz
Thu Jun 26 00:23:27 EDT 2008
On 26 Jun 2008, at 8:14 am, Andrew Wagner wrote:
> 6.) You have a [(WeatherStationId, Latitude, Longitude)]. Similar to
> #3, write a function which will, off-line, turn this into a data
> structure from which you can easily determine the nearest Weather
> Station, given an arbitrary Latitude and Longitude.
I actually set something not entirely unlike this as a problem in
a 4th year OO class. Despite telling them over and over and over
again that the Earth is not flat, and despite telling them how to
convert (Latitude, Longitude) to 3-dimensional coordinates on the
unit sphere, and despite telling them that greatest circle distance
between two points on the surface of the Earth is a monotone
function of Euclidean distance between points on the unit sphere,
so that all they had to do was to glue these pieces together,
EVERY SINGLE ONE used Euclidean distance between (Latitude,
Longitude) pairs as if they were co-ordinates on a flat 2-d plane.
And we even live near the International Date Line, which is where
this mistake goes horribly wrong.
Did they score you on coding or on geometry?
For what it's worth, a 3-dimensional kd tree really flew on this
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