php method to get random combinations from specified numbers

<?php/**
 * 获取指定数字的随机数字组合
 * @param  Int    $var 数字
 * @param  Int    $num 组合这个数字的数量
 * @return Array
 */function getNumGroups($var, $num){
    // 数量不正确
    if($var<$num){        return array();
    }    $total = 0;    $result = array();    for($i=1; $i<$num; $i++){        $tmp = mt_rand(1, $var-($num-$i)-$total);        $total += $tmp;        $result[] = $tmp;
    }    $result[] = $var-$total;    return $result;
}// demo$result = getNumGroups(100, 3);
print_r($result);?>

Array(
    [0] => 42
    [1] => 25
    [2] => 33)