長ったらしい分わかりやすいかもしれない私のPHPでのコードを以下に掲載いたします。
<?php
$input = explode(' ', trim(fgets(STDIN)));
$old_str_len = $input[0];
$new_str_len = $input[1];
$old_str = trim(fgets(STDIN));
$new_str = trim(fgets(STDIN));
$old_str_chars = str_split($old_str);
$new_str_chars = str_split($new_str);
$order_count = 0;
$checked_old_char_memo = array();
$checked_new_char_memo = array();
foreach ($old_str_chars as $char) {
if (isset($checked_old_char_memo[$char])) {
$checked_old_char_memo[$char]++;
} else {
$checked_old_char_memo[$char] = 1;
}
}
foreach ($new_str_chars as $char) {
if (isset($checked_new_char_memo[$char])) {
$checked_new_char_memo[$char]++;
} else {
$checked_new_char_memo[$char] = 1;
}
}
foreach ($checked_new_char_memo as $char => $count) {
if (!array_key_exists($char, $checked_old_char_memo)) {
$order_count += $count;
} elseif (array_key_exists($char, $checked_old_char_memo) && $checked_old_char_memo[$char] - $count < 0) {
$order_count += $count - $checked_old_char_memo[$char];
}
}
echo $order_count."\n";