Question

我有一个整数值的数组（超过4个键）。我必须选择4个不同的值，这样这些数字的平均值将等于给定一个或如果不可能则为假。最好的方法是什么？（算法）

Answer 1

如何实现它是找到给定长度的数组的所有可能子集，然后遍历它们并计算它们的平均值：

function get_subset_with_average($average, Array $data, $length) {
    // Make sure we can calculate the subsets
    if (count($data) < $length) {
        throw new Exception("The subset length is more than the size of the array");
    }
    $a = $b = 0;
    $subset = [];
    $subsets = [];

    // Loop through the data and get all subset combinations
    while ($a < count($data)) {
        $current = $data[$a++];
        $subset[] = $current;
        if (count($subset) == $length) {
            $subsets[] = $subset;
            array_pop($subset);
        }
        if ($a == count($data)) {
            $a = ++$b;
            $subset = [];
        }
    }

    // Loop through the subsets and check if the average equals the desired average
    foreach ($subsets as $set) {
        if (array_sum($set) / count($set) == $average) {
            return $set;
        }
    }
    return false;
}
$data = array(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15);

var_dump(get_subset_with_average(2.5, $data, 4));
var_dump(get_subset_with_average(5.75, $data, 4));
var_dump(get_subset_with_average(9.3, $data, 4));
var_dump(get_subset_with_average(13, $data, 4));

这将输出：

array(4) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(3)
  [3]=>
  int(4)
}
array(4) {
  [0]=>
  int(2)
  [1]=>
  int(3)
  [2]=>
  int(4)
  [3]=>
  int(14)
}
bool(false)
bool(false)

php排序数组的平均值

1 个答案: