Question

How to find the shortest identical consecutive subarray in an array with PHP

Answer 1

function shortest_identical_consecutive_subarray(array $arr): array
{
    if (count($arr) === 0) {
        return [];
    }

    $bestStart = 0;
    $bestLen   = count($arr);

    $currentStart = 0;
    $currentLen   = 1;

    for ($i = 1; $i < count($arr); $i++) {
        if ($arr[$i] === $arr[$i - 1]) {
            $currentLen++;
        } else {
            if ($currentLen < $bestLen) {
                $bestLen  = $currentLen;
                $bestStart = $currentStart;
            }
            $currentStart = $i;
            $currentLen   = 1;
        }
    }

    if ($currentLen < $bestLen) {
        $bestLen  = $currentLen;
        $bestStart = $currentStart;
    }

    return array_slice($arr, $bestStart, $bestLen);
}

// ------------------------------------------------------------
// MAIN PROGRAM
// ------------------------------------------------------------

$arr = [
    3,3,3,
    7,7,7,7,7,
    2,2,
    5,5,5,5,
    9,9,9,9,9,9
];

$resultArr = shortest_identical_consecutive_subarray($arr);

echo "Array result: ";
foreach ($resultArr as $x) {
    echo $x . " ";
}



/*
run:

Array result: 2 2 

*/

 

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