The weekly challenge 380 - Task 2: Reverse Degree

  1 #!/usr/bin/env perl
  2 # https://theweeklychallenge.org/blog/perl-weekly-challenge-380/#TASK2
  3 #
  4 # Task 2: Reverse Degree
  5 # ======================
  6 #
  7 # You are given a string.
  8 #
  9 # Write a script to find the reverse degree of the given string.
 10 #
 11 ##  For each character, multiply its position in the reversed alphabet (‘a’ =
 12 ##  26, ‘b’ = 25, …, ‘z’ = 1) with its position in the string. Sum these products
 13 ##  for all characters in the string to get the reverse degree.
 14 #
 15 ## Example 1
 16 ##
 17 ## Input: $str = "z"
 18 ## Output: 1
 19 ##
 20 ## Reverse alphabet value of "z" is 1.
 21 ## Position 1: 1 x 1
 22 ## Sum of product: 1
 23 #
 24 ## Example 2
 25 ##
 26 ## Input: $str = "a"
 27 ## Output: 26
 28 ##
 29 ## Reverse alphabet value of "a" is 26.
 30 ## Position 1: 1 x 26
 31 ## Sum of product: 26
 32 #
 33 ## Example 3
 34 ##
 35 ## Input: $str = "bbc"
 36 ## Output: 147
 37 ##
 38 ## Reverse alphabet value of "b" is 25 and "c" is 24.
 39 ## Position 1: 1 x 25
 40 ## Position 2: 2 x 25
 41 ## Position 3: 3 x 24
 42 ## Sum of product: 25 + 50 + 72 => 147
 43 #
 44 ## Example 4
 45 ##
 46 ## Input: $str = "racecar"
 47 ## Output: 560
 48 ##
 49 ## Reverse alphabet value of "r" is 9, "a" is 26, "c" is 24 and "e" is 24.
 50 ## Position 1: 1 x 9
 51 ## Position 2: 2 x 26
 52 ## Position 3: 3 x 24
 53 ## Position 4: 4 x 22
 54 ## Position 5: 5 x 24
 55 ## Position 6: 6 x 26
 56 ## Position 7: 7 x 9
 57 ## Sum of product: 9 + 52 + 72 + 88 + 120 + 156 + 63
 58 #
 59 ## Example 5
 60 ##
 61 ## Input: $str = "zyx"
 62 ## Output: 14
 63 ##
 64 ## Reverse alphabet value of "z" is 1, "y" is 2 and "x" is 3.
 65 ## Position 1: 1 x 1
 66 ## Position 2: 2 x 2
 67 ## Position 3: 3 x 3
 68 ## Sum of product: 1 + 4 + 9
 69 #
 70 ############################################################
 71 ##
 72 ## discussion
 73 ##
 74 ############################################################
 75 #
 76 # We split the string into its individual characters. For the position,
 77 # we just keep count. For the reverse alphabet value, we pick ord() of
 78 # the character and remove 97 (which is the alphabet value in the range
 79 # 0..25), then we remove the result from 26 to get the reverse alphabet
 80 # value in the range 1..26. We then just need to multiply the position
 81 # with the current value, then add the result to the sum.
 82 
 83 use v5.36;
 84 
 85 reverse_degree("z");
 86 reverse_degree("a");
 87 reverse_degree("bbc");
 88 reverse_degree("racecar");
 89 reverse_degree("zyx");
 90 
 91 sub reverse_degree($str) {
 92    say "Input: \"$str\"";
 93    my $pos = 0;
 94    my $sum = 0;
 95    foreach my $char (split //, $str) {
 96       $pos++;
 97       my $rev = 26 - (ord($char) - 97);
 98       $sum += ($pos * $rev);
 99    }
100    say "Output: $sum";
101 }