Input: $s = "Perl" $t = "Preel"
Output: "e"

Input: $s = "Weekly" $t = "Weeakly"
Output: "a"

Input: $s = "Box" $t = "Boxy"
Output: "y"

sub oddChar($s, $t) {
  # count the characters in $s
  my %count;
  for $s.lc.split('', :skip-empty) -> $c {
    %count{$c}++;
  }
  # find the character in $t that's been added to $s
  for $t.lc.split('', :skip-empty) -> $c {
    if ( %count{$c}:!exists ) {
      # we found the added character!
      return $c
    }
    %count{$c}--;
    %count{$c}:delete if %count{$c} == 0;
  }
  die "No odd character found!";
}

sub oddChar($s, $t) {
  # count the characters in $s
  my %count;
  foreach my $c ( split(//, lc($s)) ) {
    $count{$c}++;
  }
  # find the character in $t that's been added to $s
  foreach my $c ( split(//, lc($t)) ) {
    if ( ! exists $count{$c} ) {
      # we found the added character!
      return $c
    }
    $count{$c}--;
    delete $count{$c} if $count{$c} == 0;
  }
  die "No odd character found!";
}

import sys
from collections import Counter

def oddChar(s, t):
    # count the characters in s
    count = Counter()
    for c in s.lower():
        count[c] += 1

    # find the character in t that's been added to s
    for c in t.lower():
        if c not in count:
            # we found the added character!
            return c
        count[c] -= 1
        if count[c] == 0:
            del count[c]

    sys.exit("No odd character found!")

Input: $p = "Joe hit a ball, the hit ball flew far after it was hit."
       $w = "hit"
Output: "ball"

The banned word "hit" occurs 3 times.
The other word "ball" occurs 2 times.

Input: $p = "Perl and Raku belong to the same family. Perl is the most popular language in the weekly challenge."
       $w = "the"
Output: "Perl"

The banned word "the" occurs 3 times.
The other word "Perl" occurs 2 times.

Example 1:
Input: $p = "Joe hit a ball, the hit ball flew far after it was hit."
       $w = "hit"
Output: "hit."

The banned word "hit" occurs 2 times.
The other word "hit." occurs 1 time.

sub frequentWord($p, $w) {
  # assign the value to a container so we can modify it
  my $paragraph = $p;

  # first, remove punctuation from the paragraph
  # (but we'll leave apostrophes for contractions)
  $paragraph ~~ s:i:g/<-[a..z'\s]>//;

  # count the words in $paragraph
  my %count;
  for $paragraph.lc.split(' ', :skip-empty) -> $pw {
    %count{$pw}++;
  }

  # generate the output about the banned word
  my $bannedCount = %count{$w} // 0;
  my $output = qq/The banned word "$w" occurs $bannedCount /;
  $output ~= ($bannedCount == 1) ?? 'time' !! 'times';
  $output ~= ".\n";

  # delete the banned word from the word count
  %count{$w}:delete;

  # now find the most frequent word left and report on that
  my @sorted = %count.keys.sort: {
    # sort by count
    %count{$^b} <=> %count{$^a}
  };
  my $freqWord  = @sorted[0];
  my $freqCount = %count{$freqWord};

  $output ~= qq/The other word "$freqWord" /;
  $output ~= qq/occurs $freqCount /;
  $output ~= ($freqCount == 1) ?? 'time.' !! 'times.';

  return $freqWord, $output;
}

Example 1:
Input: $p = "Joe hit a ball, the hit ball flew far after it was hit."
       $w = "hit"
Output: "ball"

The banned word "hit" occurs 3 times.
The other word "ball" occurs 2 times.

sub frequentWord($p, $w) {
  # first, remove punctuation from the paragraph
  # (but we'll leave apostrophes for contractions)
  $p =~ s/[^a-z'\s]//ig;

  # count the words in $paragraph
  my %count;
  foreach my $pw ( split(/\s+/, lc($p)) ) {
    $count{$pw}++;
  }

  # generate the output about the banned word
  my $bannedCount = $count{$w} // 0;
  my $output = qq/The banned word "$w" occurs $bannedCount /;
  $output .= ($bannedCount == 1) ? 'time' : 'times';
  $output .= ".\n";

  # delete the banned word from the word count
  delete $count{$w};

  # now find the most frequent word left and report on that
  my @sorted = sort {
    # sort by count
    $count{$b} <=> $count{$a}
  } keys %count;
  my $freqWord  = $sorted[0];
  my $freqCount = $count{$freqWord};

  $output .= qq/The other word "$freqWord" /;
  $output .= qq/occurs $freqCount /;
  $output .= ($freqCount == 1) ? 'time.' : 'times.';

  return $freqWord, $output;
}

import re
from collections import Counter

def frequentWord(p, w):
    # first, remove punctuation from the paragraph
    # (but we'll leave apostrophes for contractions)
    p = re.sub(r'[^a-z\'\s]', '', p.lower())

    # count the words in $paragraph
    count = Counter()
    for pw in p.split():
        count[pw] += 1

    # generate the output about the banned word
    bannedCount = count[w] if w in count else 0
    output = f'The banned word "{w}" occurs {bannedCount} ';
    output += 'time' if bannedCount == 1 else 'times'
    output += ".\n"

    # delete the banned word from the word count
    del count[w]

    # now find the most frequent word left and report on that
    decorated = [ ( count[w], w ) for w in count.keys() ]
    sorted_tuples = sorted(
        decorated,
        # the - before the first element sorts descending
        key=lambda k: -k[0]
    )
    freqWord = sorted_tuples[0][1]
    freqCount = count[freqWord]

    output +=  f'The other word "{freqWord}" '
    output += f'occurs {freqCount} '
    output += 'time.' if freqCount == 1 else 'times.'

    return (freqWord, output)