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| -rw-r--r-- | challenge-143/james-smith/README.md | 43 |
1 files changed, 6 insertions, 37 deletions
diff --git a/challenge-143/james-smith/README.md b/challenge-143/james-smith/README.md index 67a6742064..d7d0f3e04a 100644 --- a/challenge-143/james-smith/README.md +++ b/challenge-143/james-smith/README.md @@ -10,7 +10,7 @@ submit solutions in whichever language you feel comfortable with. You can find the solutions here on github at: -https://github.com/drbaggy/perlweeklychallenge-club/tree/master/challenge-143/james-smith/perl +https://github.com/drbaggy/perlweeklychallenge-club/tree/master/challenge-143/james-smith # Challenge 1 - Calculator @@ -32,44 +32,13 @@ sub evaluate { ***You are given a positive number, `$n`. Write a script to find out if the given number is Stealthy Number. A positive integer `N` is stealthy, if there exist positive integers `a`, `b`, `c`, `d` such that `a * b = c * d = N` and `a + b = c + d + 1`.*** -To perform a sleep sort - we loop through the list of numbers, sleeping for `$value` seconds and updating the list of results with `$value` - ## The solution -We need to parallelise this process - -There are different ways of doing this `fork`, `threads`, `Promises`. - -We will go for the `threads` approach as it easier to implement that `Promises` but doesn't eat at memory by forking lots of times. - ```perl -use threads; -use threads::shared; -use Time::HiRes qw(sleep); - -my @res :shared; -my @list=map{0.001*int rand 3000}1..20; - -say "@list"; - -sub sleeper {sleep$_[0];push@res,$_[0]} - -threads->new( \&sleeper, $_ ) for @list; - -$_->join for threads->list; - -say for @res; +sub stealthy_number { + my($n,%c) = shift; + $n%$_||($c{$n/$_+$_ }++,$c{$n/$_+$_+1}++) for 1..sqrt$n; + (grep { $_ > 1 } values %c) ? 1 : 0; +} ``` -## Notes - - * We create a test set of 20 values between `0` and `3`. - * We fire off all the threads (`threads->new`) - * Wait for them to finish `$_->join for threads->list` - * Return the results. - * As well as `use threads`, we also `use threads::shared`. This lets us declare the results array `@res` shareable across all processes, which we need to collect the values. - -## Caveat - -Not all threads start at the same time so sometimes results don't quite come back in the same order - especially if values are close together. - |