/**
* Finds the maximum distance between two values in an array.
*
* Distance is defined as the absolute difference
* between the indices of the two values.
*
* @param array $numbers Input array.
* @param int $value1 First value to find.
* @param int $value2 Second value to find.
*
* @return int Maximum distance, or -1 if either value is not found.
*/
function maxDistanceBetweenValues(array $numbers, int $value1, int $value2): int
{
$firstValue1 = -1;
$lastValue1 = -1;
$firstValue2 = -1;
$lastValue2 = -1;
// Find the first and last occurrence of both values.
foreach ($numbers as $index => $value) {
if ($value === $value1) {
if ($firstValue1 === -1) {
$firstValue1 = $index;
}
$lastValue1 = $index;
}
if ($value === $value2) {
if ($firstValue2 === -1) {
$firstValue2 = $index;
}
$lastValue2 = $index;
}
}
// One or both values were not found.
if ($firstValue1 === -1 || $firstValue2 === -1) {
return -1;
}
// Check the extreme combinations.
$distance1 = abs($firstValue1 - $lastValue2);
$distance2 = abs($firstValue2 - $lastValue1);
return max($distance1, $distance2);
}
// Example
$array = [2, 3, 7, 3, 3, 4, 8, 8, 8, 11, 9, 1, 3];
$result = maxDistanceBetweenValues($array, 3, 8);
echo "Maximum distance between 3 and 8: {$result}" . PHP_EOL;
/*
run:
Maximum distance between 3 and 8: 7
*/
