Problem 502. Would Homer Like It?
Given a matrix of ones and zeros, you must determine if there are any doughnuts present (would Homer Simpson like it?). A doughnut is a 4-connected region of ones completely enclosing a 4-connected region of zeros. You can assume that any regions of ones are either blobs (or genus 0) or doughnuts (genus 1). Thus if you find any hole in a region of ones, it is a doughnut. Also, there are no nested doughnuts.
Return true if any doughnuts are present, otherwise false.
Examples:
This is a doughnut:
1 1 1
1 0 1
1 1 1
Here is another doughnut:
0 0 0 1 1 1
0 1 1 1 0 1
0 0 1 0 0 1
0 0 1 1 1 1
This is not a doughnut:
0 1 0
1 0 1
0 1 0
because the ones are not 4-connected and so can't surround anything.
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Alfonso Nieto-Castanon
on 15 Mar 2012
mmm... the image processing toolbox seems to be available again?
Ned Gulley
on 16 Mar 2012
Oh! Thanks for pointing that out. It will disappear again shortly. Sorry about that.
Alfonso Nieto-Castanon
on 16 Mar 2012
Sounds good (it was too easy this way)
Ned Gulley
on 19 Mar 2012
Okay, we should be back to no-toolbox coding.
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