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| -rw-r--r-- | challenge-198/jeanluc2020/blog-1.txt | 1 | ||||
| -rw-r--r-- | challenge-198/jeanluc2020/blog-2.txt | 1 | ||||
| -rwxr-xr-x | challenge-198/jeanluc2020/perl/ch-1.pl | 62 | ||||
| -rwxr-xr-x | challenge-198/jeanluc2020/perl/ch-2.pl | 65 |
4 files changed, 129 insertions, 0 deletions
diff --git a/challenge-198/jeanluc2020/blog-1.txt b/challenge-198/jeanluc2020/blog-1.txt new file mode 100644 index 0000000000..4c11c54f7a --- /dev/null +++ b/challenge-198/jeanluc2020/blog-1.txt @@ -0,0 +1 @@ +http://gott-gehabt.de/800_wer_wir_sind/thomas/Homepage/Computer/perl/theweeklychallenge-198-1.html diff --git a/challenge-198/jeanluc2020/blog-2.txt b/challenge-198/jeanluc2020/blog-2.txt new file mode 100644 index 0000000000..0b29407527 --- /dev/null +++ b/challenge-198/jeanluc2020/blog-2.txt @@ -0,0 +1 @@ +http://gott-gehabt.de/800_wer_wir_sind/thomas/Homepage/Computer/perl/theweeklychallenge-198-2.html diff --git a/challenge-198/jeanluc2020/perl/ch-1.pl b/challenge-198/jeanluc2020/perl/ch-1.pl new file mode 100755 index 0000000000..0f9d904851 --- /dev/null +++ b/challenge-198/jeanluc2020/perl/ch-1.pl @@ -0,0 +1,62 @@ +#!/usr/bin/perl +# https://theweeklychallenge.org/blog/perl-weekly-challenge-198/#TASK1 +# +# You are given a list of integers, @list. +# +# Write a script to find the total pairs in the sorted list where 2 consecutive +# elements has the max gap. If the list contains less then 2 elements then +# return 0. +# +## Example 1 +## +## Input: @list = (2,5,8,1) +## Output: 2 +## +## Since the sorted list (1,2,5,8) has 2 such pairs (2,5) and (5,8) +# +## Example 2 +## +## Input: @list = (3) +## Output: 0 +# +### This is a pretty straightforward problem. Let's just walk the array, +### calculate the gap of 2 consecutive values, remember this instance, and in +### the end display the value for the maximum of the gaps + +use strict; +use warnings; +use feature 'say'; +use List::Util qw(max); + +# some examples of lists +my $lists = [ + [ 2, 5, 8, 1 ], + [ 3 ], + [ 1, 2, 3, 5, 7, 9, 13, 17], + [ 1, 3, 7, 4, 9, 11 ] +]; + +# let's generate the output for all examples +foreach my $list ( @$lists ) { + say "(" . join(", ", @$list) . ") returns " . max_gap(@$list); +} + +# let's calculate the gaps +sub max_gap { + my @list = sort { $a <=> $b } @_; + my $gaps; + # if the list contains less than 2 elements then return 0 + return 0 if scalar(@list) < 2; + my $last = undef; + foreach my $elem (@list) { + if(defined($last)) { + # we're at least at the second element, so let's calculate the gap + # to the previous element and count this instance + $gaps->{ $elem - $last }++; + } + $last = $elem; + } + # return the number of instances for the max gap + return $gaps->{ max(keys %$gaps) }; +} + diff --git a/challenge-198/jeanluc2020/perl/ch-2.pl b/challenge-198/jeanluc2020/perl/ch-2.pl new file mode 100755 index 0000000000..1da1592347 --- /dev/null +++ b/challenge-198/jeanluc2020/perl/ch-2.pl @@ -0,0 +1,65 @@ +#!/usr/bin/perl +# https://theweeklychallenge.org/blog/perl-weekly-challenge-198/#TASK2 +# +# You are given an integer $n > 0. +# +# Write a script to print the count of primes less than $n. +# +## Example 1 +## +## Input: $n = 10 +## Output: 4 as in there are 4 primes less than 10 are 2, 3, 5 ,7. +# +## Example 2 +## +## Input: $n = 15 +## Output: 6 +# +## Example 3 +## +## Input: $n = 1 +## Output: 0 +# +## Example 4 +## +## Input: $n = 25 +## Output: 9 +# +### This is a nice little task, so let's just simply count all the primes +### up to $n-1 (since we want to count primes that are less than $n) +### To do that, just check each of the integers up to $n whether it is +### prime or not and increment a counter if it is + +use strict; +use warnings; +use feature 'say'; + +my @examples = (10, 15, 1, 25, 23, 30, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000); + +foreach my $n (@examples) { + say "There are " . count_primes($n) . " primes < $n"; +} + +# count all the primes < $n +sub count_primes { + my $n = shift; + my $count = 0; + # since we're only interested in primes less than $n, we only look for + # primes up to $n-1. Should $n be a prime itself, we don't count it + foreach my $i (1..$n-1) { + $count++ if is_prime($i); # increment $count in case we have a prime + } + return $count; +} + +# helper function to check wether an integer is a prime +sub is_prime { + my $n = shift; + return 0 if $n < 2; # 1 isn't prime + foreach(2..sqrt($n)) { + # if any integer < sqrt($n) divides $n, we don't have a prime + return 0 unless $n % $_; + } + # since we didn't find any integer that divides $n, we have a prime + return 1; +} |