作业：
[user => [username, realname], scores[], rank]
$standings = [];
foreach ($usernames as $username) {
$user = queryUser($username);
$row = ['total_score' => 0];
$row['user'] = [
'username' => $user['username'],
'realname' => $user['realname'],
];
foreach ($problem_ids as $problem_id) {
$cond = "submitter = '{$user['username']}' AND problem_id = $problem_id";
$submission = DB::selectFirst("SELECT id, score FROM submissions INNER JOIN (SELECT MAX(score) AS score FROM submissions WHERE $cond) AS max USING (score) WHERE $cond ORDER BY submit_time DESC");
if ($submission) {
$row['scores'][] = [
'submission_id' => $submission['id'],
'score' => intval($submission['score']),
];
$row['total_score'] += $submission['score'];
} else {
$row['scores'][] = null;
}
}
$standings[] = $row;
}
usort($standings, function($lhs, $rhs) {
if ($lhs['total_score'] != $rhs['total_score']) {
return $rhs['total_score'] - $lhs['total_score'];
}
return strcmp($lhs['user']['username'], $rhs['user']['username']);
});
?>