# You are given a string containing only digits (0..9). The string should have
# between 4 and 12 digits.
#
# Write a script to print every possible valid IPv4 address that can be made by
# partitioning the input string.
#
# For the purpose of this challenge, a valid IPv4 address consists of four
# “octets” i.e. A, B, C and D, separated by dots (.).
#
# Each octet must be between 0 and 255, and must not have any leading zeroes.
# (e.g., 0 is OK, but 01 is not.)
#
# Example
#
# Input: 25525511135,
#
# Output:
#
# 255.255.11.135
# 255.255.111.35

sub parse-to-ipv4($s) {
    gather for $s ~~ m:ex/ ^ ((\d ** 1..3) <?{ $0 < 256 }>) ** 4 $ / -> $r {
        take $r[0].join('.');
    }
}

parse-to-ipv4('25525511135').say;
parse-to-ipv4('127001').say;
parse-to-ipv4('0000').say;