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Problem 2045. Only once: cleaning up your columns

Created by J-G van der Toorn

We have a logical array (with ones and zeroes). It is simple: after processing every column may only contain a single true value, or none at all. Not on any row, but only the uppermost occurrence in the input array, if any.

For example:

 [ 0 0 1 1
   0 1 0 1
   0 0 1 1 ] 
becomes 
 [ 0 0 1 1
   0 1 0 0
   0 0 0 0 ] 

And of course, your solution should be the most innovative, shortest and most elegant one.

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Solution Statistics

16 correct solutions 6 incorrect solutions
Last solution submitted on Aug 14, 2014

Problem Comments