Given two arrays combine common values - php

Question

$names = ['john','brian','john','steven','michael','paul','mark','paul','brian'];
$money = [2, 4, 3, 7, 5, 8, 20, -2, 4];
The indexes of $names and $money correspond to each other.
I need to find the most efficient way to add common $money to each $names and print only the even values.
For example, john appears two times, with 2 and 3 money. So johnhas 5 money.
Desired output:
mark: 20
brian: 8
paul: 6
I am thinking of looping through each array, but this is O(n^2) Is there an easier way?

Answer 1

Make associative array (hash) for result:
$names = ['john','brian','john','steven','michael','paul','mark','paul','brian'];
$money = [2, 4, 3, 7, 5, 8, 20, -2, 4];
$result = [];
for ($i = 0; $i < count($names); $i++) {
if (!isset($result[$names[$i]])) {
$result[$names[$i]] = 0;
}
$result[$names[$i]] += $money[$i];
}
arsort($result); // reverse (big first) sort by money
print_r($result);

Answer 2

just loop through names and use it keys for money array:
$names = ['john','brian','john','steven','michael','paul','mark','paul','brian'];
$money = [2, 4, 3, 7, 5, 8, 20, -2, 4];
$res = [];
foreach ($names as $key => $value) {
$res[$value] = isset($res[$value]) ? $res[$value] + $money[$key] : $money[$key];
}
var_dump($res);

Answer 3

You just have to loop through $names once and set name as key in a result- variable.
$names = ['john','brian','john','steven','michael','paul','mark','paul','brian'];
$money = [2, 4, 3, 7, 5, 8, 20, -2, 4];
$data = [];
foreach ($names as $key => $name) {
if (!isset($data[$name])) {
$data[$name] = 0;
}
$data[$name] += $money[$key];
}
print_r($data);

Answer 4

Maybe you'll need a check, if both arrays have the same size.
$names = ['john','brian','john','steven','michael','paul','mark','paul','brian'];
$money = [2, 4, 3, 7, 5, 8, 20, -2, 4];
$result = [];
foreach ($names as $index => $name) {
if (empty($result[$name]) {
$result[$name] = $money[$index];
} else {
$result[$name] += $money[$index];
}
}
print_r($result);