The traffic arriving at a junction is observed for an hour. Each minute the number of arrivals at the junction is recorder and the data tabulated:
| Number of arrivals in each one minute period | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | Number of one minute periods having that number of arrivals | 4 | 15 | 12 | 9 | 6 | 5 | 3 | 1 | 2 | 1 | 1 |
Design a function to return a random number based on this distribution.
Generalise the function to use a similar distribution as a parameter.
PHP:
<? $traffic = array( 0 => 4, 1 => 15, 2 => 12, 3 => 9, 4 => 6, 5 => 5, 6 => 3, 7 => 1, 8 => 2, 9 => 1, 10 => 1 ); $pos = mt_rand(1, 60); foreach($traffic as $key => $minute) { $total += $minute; if ($total >= $pos) { echo $key; break; } }?>Which produces:
3
That seemed a bit easy, so I thought I'd have a go at trying to make the smallest possible solution:
<?$t=array(4,15,12,9,6,5,3,1,2,1,1);$p=rand(1,60);for($n=0;$a<$p;)$a+=$t[$n++];echo --$n?>Which produces:
5