The weekly challenge 387 - Task 1: Rearrange Binary String

 1 #!/usr/bin/env perl
 2 # https://theweeklychallenge.org/blog/perl-weekly-challenge-387/#TASK1
 3 #
 4 # Task 1: Rearrange Binary String
 5 # ===============================
 6 #
 7 # You are given a binary string string.
 8 #
 9 # Write a script to re-arrange the given binary string that all occurrences of
10 # “01” are simultaneously replaced with “10” until no occurrences of “01”
11 # exist. Finally return the total steps needed.
12 #
13 ## Example 1
14 ##
15 ## Input: $str = "111000"
16 ## Output: 0
17 ##
18 ## The string already has all 1s on the left and 0s on the right.
19 ## There are no occurrences of "01", so zero step needed.
20 #
21 ## Example 2
22 ##
23 ## Input: $str = "00011"
24 ## Output: 4
25 ##
26 ## Step 1: "00101"
27 ## Step 2: "01010"
28 ## Step 3: "10100"
29 ## Step 4: "11000"
30 #
31 ## Example 3
32 ##
33 ## Input: $str = "01011"
34 ## Output: 3
35 ##
36 ## Step 1: "10101"
37 ## Step 2: "11010"
38 ## Step 3: "11100"
39 #
40 ## Example 4
41 ##
42 ## Input: $str = "010101"
43 ## Output: 3
44 ##
45 ## Step 1: "101010"
46 ## Step 2: "110100"
47 ## Step 3: "111000"
48 #
49 ## Example 5
50 ##
51 ## Input: $str = "00001"
52 ## Output: 4
53 ##
54 ## Step 1: "00010"
55 ## Step 2: "00100"
56 ## Step 3: "01000"
57 ## Step 4: "10000"
58 #
59 ############################################################
60 ##
61 ## discussion
62 ##
63 ############################################################
64 #
65 # While the string still contains "01" as a substring, replace
66 # all "01" for "10". Count how many steps were taken.
67 
68 use v5.36;
69 
70 rearrange_binary_string("111000");
71 rearrange_binary_string("00011");
72 rearrange_binary_string("01011");
73 rearrange_binary_string("010101");
74 rearrange_binary_string("00001");
75 
76 sub rearrange_binary_string($str) {
77    say "Input: \"$str\"";
78    my $count = 0;
79    while($str =~ m/01/) {
80       $str =~ s/01/10/g;
81       $count++;
82    }
83    say "Output: $count";
84 }