The weekly challenge 334 - Task 1: Range Sum

 1 #!/usr/bin/env perl
 2 # https://theweeklychallenge.org/blog/perl-weekly-challenge-334/#TASK1
 3 #
 4 # Task 1: Range Sum
 5 # =================
 6 #
 7 # You are given a list integers and pair of indices..
 8 #
 9 # Write a script to return the sum of integers between the given indices (inclusive).
10 #
11 ## Example 1
12 ##
13 ## Input: @ints = (-2, 0, 3, -5, 2, -1), $x = 0, $y = 2
14 ## Output: 1
15 ##
16 ## Elements between indices (0, 2) => (-2, 0, 3)
17 ## Range Sum: (-2) + 0 + 3 => 1
18 #
19 #
20 ## Example 2
21 ##
22 ## Input: @ints = (1, -2, 3, -4, 5), $x = 1, $y = 3
23 ## Output: -3
24 ##
25 ## Elements between indices (1, 3) => (-2, 3, -4)
26 ## Range Sum: (-2) + 3 + (-4) => -3
27 #
28 #
29 ## Example 3
30 ##
31 ## Input: @ints = (1, 0, 2, -1, 3), $x = 3, $y = 4
32 ## Output: 2
33 ##
34 ## Elements between indices (3, 4) => (-1, 3)
35 ## Range Sum: (-1) + 3 => 2
36 #
37 #
38 ## Example 4
39 ##
40 ## Input: @ints = (-5, 4, -3, 2, -1, 0), $x = 0, $y = 3
41 ## Output: -2
42 ##
43 ## Elements between indices (0, 3) => (-5, 4, -3, 2)
44 ## Range Sum: (-5) + 4 + (-3) + 2 => -2
45 #
46 #
47 ## Example 5
48 ##
49 ## Input: @ints = (-1, 0, 2, -3, -2, 1), $x = 0, $y = 2
50 ## Output: 1
51 ##
52 ## Elements between indices (0, 2) => (-1, 0, 2)
53 ## Range Sum: (-1) + 0 + 2 => 1
54 #
55 ############################################################
56 ##
57 ## discussion
58 ##
59 ############################################################
60 #
61 # We just need to calculate the sum of a slice of the input array.
62 # We use sum() from List::Util which makes the whole operation really
63 # easy and quick.
64 
65 use v5.36;
66 
67 use List::Util qw( sum );
68 
69 range_sum( [-2, 0, 3, -5, 2, -1], 0, 2);
70 range_sum( [1, -2, 3, -4, 5], 1, 3);
71 range_sum( [1, 0, 2, -1, 3], 3, 4);
72 range_sum( [-5, 4, -3, 2, -1, 0], 0, 3);
73 range_sum( [-1, 0, 2, -3, -2, 1], 0, 2);
74 
75 sub range_sum($ints, $x, $y) {
76     say "Input: (" . join(", ", @$ints) . "), $x, $y";
77     say "Output: " . sum( @$ints[$x..$y] );
78 }