Divide integer by qualifying rows and add to column values - php

Question

I need the variable $tsp to be evenly added to the value in the "count" field, but only in those fields where the "count" is greater than 0 .
$tsp = 9;
$fin = [
"1701" => ["total_space" => 0, "count" => 0],
"1702" => ["total_space" => 0, "count" => 0],
"1703" => ["total_space" => 20, "count" => 20],
"1704" => ["total_space" => 28, "count" => 28]
];
that 's what the result should be
$tsp = 9;
$fin = [
"1701" => ["total_space" => 0, "count" => 0],
"1702" => ["total_space" => 0, "count" => 0],
"1703" => ["total_space" => 20, "count" => 25], // +5
"1704" => ["total_space" => 28, "count" => 32] // +4
];
I wrote a loop, but it increases both fields by 9,
for ($i = $tsp; $i > 0; $i--) {
foreach ($fin as $dt => $s) {
if ($s['count'] > 0) {
$fin[$dt]['count'] = $s['count'] + 1;
$tsp = $tsp - 1;
}
}
}

Answer 1

The issue with your attempted implementation is that you iterate over all entries in the $fin array and increment the counter for each $tsp. You only want to increment one of those, not all ...
This would be a possible solution:
<?php
$tsp=9;
$fin = [
"1701"=> ["total_space"=> 0, "count"=> 0],
"1702"=> ["total_space"=> 0, "count"=> 0],
"1703"=> ["total_space"=> 20, "count"=> 20],
"1704"=> ["total_space"=> 28, "count"=> 28]
];
while ($tsp > 0) {
array_walk($fin, function(&$s) use (&$tsp) {
if ($tsp > 0 && $s['count'] > 0) {
$s['count']++;
$tsp--;
}
});
}
print_r($fin);
The output obviously is:
Array
(
[1701] => Array
(
[total_space] => 0
[count] => 0
)
[1702] => Array
(
[total_space] => 0
[count] => 0
)
[1703] => Array
(
[total_space] => 20
[count] => 25
)
[1704] => Array
(
[total_space] => 28
[count] => 32
)
)

Answer 2

Rather than brute forcing the arithmetic with single increments and decrements in a loop which re-checks for 0 counts, use a technique with lower time complexity that doesn't ever revisit 0 count rows.
My snippet filters the array once, then only adds value to qualifying rows once.
Code: (Demo)
$qualifiers = array_filter($fin, fn($row) => $row['count']);
$divideBy = count($qualifiers);
foreach ($qualifiers as $id => $row) {
$tsp -= $toAdd = ceil($tsp / $divideBy);
--$divideBy;
$fin[$id]['count'] += $toAdd;
}
var_export($fin);