Algorithm for distributing red envelopes

Find an algorithm for distributing red envelopes
We've all played with the red envelopes,
is to give a sum, a number of copies, automatically randomly allocate the amount.

The minimum amount is 0.01 yuan.

Seeking algorithm

Function ($ total, $ red packet number) {

。。。

return $ red envelope array;
}
------to solve the idea----------------------
It might be better to change it.

function Distribute ($total, $num) {
  $avg = $total/$num;
  $r = Array_fill (0, $num, $avg);

  for ($i =0; $i < $num; $i +=2) {
    $t = rand (1, $AVG * 100)/100;
    $r [$i]-= $t;
    if ($r [$i] <= 0) $r [$i] = 0.01;
    $r [$i +1] + = $t;
  }
  $r [$num-1] = $total-array_sum (array_slice ($r, 0,-1));
  return $r;
}

