diff options
| -rw-r--r-- | challenge-163/julien-fiegehenn/perl/ch-2.pl | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/challenge-163/julien-fiegehenn/perl/ch-2.pl b/challenge-163/julien-fiegehenn/perl/ch-2.pl new file mode 100644 index 0000000000..d1b93340b3 --- /dev/null +++ b/challenge-163/julien-fiegehenn/perl/ch-2.pl @@ -0,0 +1,63 @@ +#!/usr/bin/env perl +use strict; +use warnings; +use List::Util 'sum'; + +# You are given a list of positive numbers, @n. + +# Write a script to find out the summations as described below. + +# Example 1 +# Input: @n = (1, 2, 3, 4, 5) +# Output: 42 + +# 1 2 3 4 5 +# 2 5 9 14 +# 5 14 28 +# 14 42 +# 42 + +# The nth Row starts with the second element of the (n-1)th row. +# The following element is sum of all elements except first element of previous row. +# You stop once you have just one element in the row. +# Example 2 +# Input: @n = (1, 3, 5, 7, 9) +# Output: 70 + +# 1 3 5 7 9 +# 3 8 15 24 +# 8 23 47 +# 23 70 +# 70 + +sub foo { + my @rows; + $rows[0] = [@_]; + + # we'll keep going as long as we have more than 2 elements left + while ( @{ $rows[-1] } > 2 ) { + push @rows, [ + + # we always start with the 2nd element of the previous row + $rows[-1]->[1], + + # each following element is the sum of all numbers from the + # 2nd element until the position (not index, but position in + # the tabular view above) we are currently filling, of + # the previous row. + map { sum @{ $rows[-1] }[ 1 .. $_ ] } 2 .. $#{ $rows[-1] } + ]; + } + + # We're supposed to stop and return when we only have one element left, + # but it is actually easier to stop at two elements left. The last row + # is just the 2nd element of the row before, so we can return that directly. + return $rows[-1]->[-1]; +} + +use Test::More; + +is foo( 1, 2, 3, 4, 5 ), 42; +is foo( 1, 3, 5, 7, 9 ), 70; + +done_testing; |