Copyright	(c) Levent Erkok
License	BSD3
Maintainer	erkokl@gmail.com
Stability	experimental
Safe Haskell	None
Language	Haskell2010

Documentation.SBV.Examples.Puzzles.Counts

Description

Consider the sentence:

   In this sentence, the number of occurrences of 0 is _, of 1 is _, of 2 is _,
   of 3 is _, of 4 is _, of 5 is _, of 6 is _, of 7 is _, of 8 is _, and of 9 is _.

The puzzle is to fill the blanks with numbers, such that the sentence will be correct. There are precisely two solutions to this puzzle, both of which are found by SBV successfully.

References:

Douglas Hofstadter, Metamagical Themes, pg. 27.
http://mathcentral.uregina.ca/mp/archives/previous2002/dec02sol.html

Synopsis

type Count = SWord8
count :: Count -> [Count] -> [Count]
puzzle :: [Count] -> SBool
counts :: IO ()

Documentation

type Count = SWord8 Source #

We will assume each number can be represented by an 8-bit word, i.e., can be at most 128.

count :: Count -> [Count] -> [Count] Source #

Given a number, increment the count array depending on the digits of the number

puzzle :: [Count] -> SBool Source #

Encoding of the puzzle. The solution is a sequence of 10 numbers for the occurrences of the digits such that if we count each digit, we find these numbers.

counts :: IO () Source #

Finds all two known solutions to this puzzle. We have:

>>> counts
Solution #1
In this sentence, the number of occurrences of 0 is 1, of 1 is 11, of 2 is 2, of 3 is 1, of 4 is 1, of 5 is 1, of 6 is 1, of 7 is 1, of 8 is 1, of 9 is 1.
Solution #2
In this sentence, the number of occurrences of 0 is 1, of 1 is 7, of 2 is 3, of 3 is 2, of 4 is 1, of 5 is 1, of 6 is 1, of 7 is 2, of 8 is 1, of 9 is 1.
Found: 2 solution(s).