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Diffstat (limited to 'miralib/ex/hamming.m')
| -rw-r--r-- | miralib/ex/hamming.m | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/miralib/ex/hamming.m b/miralib/ex/hamming.m new file mode 100644 index 0000000..3ebb6ce --- /dev/null +++ b/miralib/ex/hamming.m @@ -0,0 +1,19 @@ +||this is a problem described by Dijkstra in his book, A Discipline of +||Programming, and attributed by him to Dr Hamming, of Bell Labs. +||Print in ascending order all numbers of the form +|| 2**a.3**b.5**c a,b,c all >=0 +||the solution here is based on a method using communicating processes. +||ham is the list of numbers, to see them, say +|| ham +||hit control-C (interrupt) when you have seen enough! + +ham = 1 : foldr1 merge [mult 2 ham, mult 3 ham, mult 5 ham] + where + mult n x = [n*a|a<-x] + merge (a:x) (b:y) = a : merge x y, if a=b + = a : merge x (b:y), if a<b + = b : merge (a:x) y, if a>b + +||Note that there is a function called `merge' in the standard +||environment, but unlike the one defined above it does not remove +||duplicates from the lists being merged. |