php method to get random combinations from specified numbers

This article mainly introduces the method of obtaining random combinations from specified numbers in PHP. Interested friends can refer to it. I hope it will be helpful to everyone.

For example: Given the number 100, you need to randomly obtain 3 combinations that make up this number, such as 70, 20, 10

The code is as follows:

<?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);

?>

##Output:

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

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