| 16 February 2024 | Challenge 256 |
Zippairs
Task 1: Maximum Pairs
Submitted by: Mohammad Sajid Anwar
You are given an array of distinct words, @words.
Write a script to find the maximum pairs in the given array. The words $words[i] and $words[j] can be a pair one is reverse of the other.
Example 1
Input: @words = ("ab", "de", "ed", "bc")
Output: 1
There is one pair in the given array: "de" and "ed"
Example 2
Input: @words = ("aa", "ba", "cd", "ed")
Output: 0
Example 3
Input: @words = ("uv", "qp", "st", "vu", "mn", "pq"))
Output: 2
Solution
As a word must not be paired with itself, we need to eliminate all palindromes from the list. Then taking a slice with the reversed words as subscripts from a hash containing the words as keys. As both members of a pair do exist in the hash, we need to half the number to get the count of pairs.
sub maximum_pairs {
(\my %words)->@{@_} = map scalar reverse, @_;
delete @words{grep $_ eq $words{$_}, keys %words};
(grep defined, @words{values %words}) / 2;
}
See the full solution.
Task 2: Merge Strings
Submitted by: Mohammad Sajid Anwar
You are given two strings, $str1 and $str2.
Write a script to merge the given strings by adding in alternative order starting with the first string. If a string is longer than the other then append the remaining at the end.
Example 1
Input: $str1 = "abcd", $str2 = "1234"
Output: "a1b2c3d4"
Example 2
Input: $str1 = "abc", $str2 = "12345"
Output: "a1b2c345"
Example 3
Input: $str1 = "abcde", $str2 = "123"
Output: "a1b2c3de"
Solution
As long as there are remaining characters in either string, we “shift” the first from both and append it to the result.
use experimental 'signatures';
sub merge_strings ($s, $t) {
my $zip;
while ($s || $t) {
$zip .= ($s && substr($s, 0, 1, '')) . ($t && substr($t, 0, 1, ''));
}
$zip;
}
See the full solution.