$ar = array(
0 =>array(
 'name' => "a",
 'time' => '879798'),
1 => array(
 'name' => "a9",
 'time' => '856565'), //85665565 ? 示例数据有问题吧，看不出是按time排序的！
2 =>array(
 'name' => "hdhdjd",
 'time' => '815465'),
3 =>array(
 'name' => "a",
 'time' => '800000'),
4 =>array(
 'name' => "dr",
 'time' => '789898'),
);

$result = array();
$len = count($ar);
for ($i = 0; $i < $len; $i ++) {
    $result[] = array_shift($ar);
    for ($j = 0; $j < count($ar); $j ++) {
        if ($ar[$j]['name'] == $result[count($result) - 1]['name']) {
            $result[] = array_splice($ar, $j, 1);
            break;
        }
    }
}

echo '<pre>';
print_r($result);

/*
Array
(
    [0] => Array
        (
            [name] => a
            [time] => 879798
        )

    [1] => Array
        (
            [0] => Array
                (
                    [name] => a
                    [time] => 800000
                )

        )

    [2] => Array
        (
            [name] => a9
            [time] => 856565
        )

    [3] => Array
        (
            [name] => hdhdjd
            [time] => 815465
        )

    [4] => Array
        (
            [name] => dr
            [time] => 789898
        )

    [5] => 
)
*/

------解决方案--------------------
有点问题，修改一下：
PHP code
$result = array();
$len = count($ar);
for ($i = 0; $i < $len - 1; $i ++) {
    $result[] = array_shift($ar);
    for ($j = 0; $j < count($ar) - 1; $j ++) {
        if ($ar[$j]['name'] == $result[count($result) - 1]['name']) {
            $item = array_splice($ar, $j, 1);
            $result[] = $item[0];
            break;
        }
    }
}

------解决方案--------------------
C/C++ code
<?php
$arr = array(
                array(
                         'name' => "a",
                         'time' => '879798'),
                array(
                         'name' => "a9",
                          'time' => '85665565'),
                array(
                         'name' => "dr",
                          'time' => '8154465'),
                array(
                         'name' => "a",
                          'time' => '800000'),
                array(
                         'name' => "dr",
                          'time' => '789898'),
);

$names = array();
$index = array();

array_walk($arr, function($val, $key){
                        global $names;