The weekly challenge 304 - Task 2: Maximum Average

 1 #!/usr/bin/env perl
 2 # https://theweeklychallenge.org/blog/perl-weekly-challenge-304/#TASK2
 3 #
 4 # Task 2: Maximum Average
 5 # =======================
 6 #
 7 # You are given an array of integers, @ints and an integer, $n which is less
 8 # than or equal to total elements in the given array.
 9 #
10 # Write a script to find the contiguous subarray whose length is the given
11 # integer, $n, and has the maximum average. It should return the average.
12 #
13 ## Example 1
14 ##
15 ## Input: @ints = (1, 12, -5, -6, 50, 3), $n = 4
16 ## Output: 12.75
17 ##
18 ## Subarray: (12, -5, -6, 50)
19 ## Average: (12 - 5 - 6 + 50) / 4 = 12.75
20 #
21 ## Example 2
22 ##
23 ## Input: @ints = (5), $n = 1
24 ## Output: 5
25 #
26 ############################################################
27 ##
28 ## discussion
29 ##
30 ############################################################
31 #
32 # We calculate the average of the first n numbers. Then, using
33 # each element of the array as the starting point, we calculate
34 # the average starting at that point (skipping sub-arrays that
35 # aren't big enough at the end). Out of all of these averages,
36 # we keep the maximum.
37 
38 use strict;
39 use warnings;
40 use List::Util qw(sum);
41 
42 maximum_average(4, 1, 12, -5, -6, 50, 3);
43 maximum_average(1, 5);
44 
45 sub maximum_average {
46    my ($n, @ints) = @_;
47    if($n > scalar(@ints) ) {
48       return print "Error: not enough elements in list!\n";
49    }
50    print "Input: n=$n, \@ints=(" . join(", ", @ints) . ")\n";
51    my $max = sum(@ints[0..$n-1]) / $n;
52    foreach my $i (1..$#ints) {
53       last if $i+$n-1 > $#ints;
54       my $avg = sum(@ints[$i..$i+$n-1]) / $n;
55       $max = $avg if $avg > $max;
56    }
57    print "Output: $max\n";
58 }