数组中的和数

Question

I have an array of numbers (zipcode-areas), like:

Array (
    [0] => 34
    [1] => 35
    [2] => 36
    [3] => 51
    [4] => 53
    [5] => 54
    [6] => 55
    [7] => 56
    [8] => 57
    [9] => 60
    [10] => 61
    [11] => 63
    [12] => 64
    [13] => 65
    [14] => 66
    [15] => 67
    [16] => 68
    [17] => 69
    [18] => 74
    [19] => 97
)

I want to sum the numbers in the array like that:

Array (
    [0] => 34-36
    [1] => 51
    [2] => 53-57
    [3] => 60-61
    [4] => 63-69
    [5] => 74
    [6] => 97
)

How can I archieve that with PHP?

Answer 1

Here is the logic to get required output.

$arr = array (34,35,36,51,53,54,55,56,57,60,61,63,64,65,66,67,68,69,74,97);

$sum_arr = array();
$prev_val = 0;

foreach($arr as $key => $val)
{
    /* Store initial value in array */
    if($key == 0)
    {
        $sum_arr[] = $val;


    }
    /* If value is not sequence */
    else if(($prev_val+1) != $val)
    {
        /* Get last index of array and append current value */
        $sum_last_idx = count($sum_arr) - 1;

        /* Append value only if both values are not equal */
        if($sum_arr[$sum_last_idx] != $prev_val)
        {
            $sum_arr[$sum_last_idx] = $sum_arr[$sum_last_idx] . '-' . $prev_val;
        }
        $sum_arr[] = $val;
    }

    /* Retain previous value */
    $prev_val = $val;
}

print_r($sum_arr);

Output

Array
(
    [0] => 34-36
    [1] => 51
    [2] => 53-57
    [3] => 60-61
    [4] => 63-69
    [5] => 74
    [6] => 97
)