The weekly challenge 302 - Task 2: Step by Step

 1 #!/usr/bin/env perl
 2 # https://theweeklychallenge.org/blog/perl-weekly-challenge-302/#TASK2
 3 #
 4 # Task 2: Step by Step
 5 # ====================
 6 #
 7 # You are given an array of integers, @ints.
 8 #
 9 # Write a script to find the minimum positive start value such that step by
10 # step sum is never less than one.
11 #
12 ## Example 1
13 ##
14 ## Input: @ints = (-3, 2, -3, 4, 2)
15 ## Output: 5
16 ##
17 ## For start value 5.
18 ## 5 + (-3) = 2
19 ## 2 + (+2) = 4
20 ## 4 + (-3) = 1
21 ## 1 + (+4) = 5
22 ## 5 + (+2) = 7
23 #
24 ## Example 2
25 ##
26 ## Input: @ints = (1, 2)
27 ## Output: 1
28 #
29 ## Example 3
30 ##
31 ## Input: @ints = (1, -2, -3)
32 ## Output: 5
33 #
34 ############################################################
35 ##
36 ## discussion
37 ##
38 ############################################################
39 #
40 # Starting with a value of 1, we calculate the step by step
41 # sum and keep trackf of the minimum. If it is < 1, we can
42 # calculate the minimum required positive start value from
43 # that minimum step sum. Otherwise we can use 1 as the result.
44 
45 use strict;
46 use warnings;
47 
48 step_by_step(-3, 2, -3, 4, 2);
49 step_by_step(1, 2);
50 step_by_step(1, -2, -3);
51 
52 sub step_by_step {
53    my @ints = @_;
54    print "Input: (" . join(", ", @ints) . ")\n";
55    my $start = 1;
56    my $min = 1;
57    foreach my $elem (@ints) {
58       $start += $elem;
59       if($start < $min) {
60          $min = $start;
61       }
62    }
63    if($min < 1) {
64       my $tmp = 2 - $min;
65       print "Output: $tmp\n";
66    } else {
67       print "Output: 1\n";
68    }
69 }