Question

How to find the starting and ending position of a given value in a sorted integer array in PHP

Answer 1

function findStartingEndingPosition($arr, $value) {
    $result = array_fill(0, 2, -1);

    $i = 0;
    for (; $i < count($arr) - 1; $i++) {
        if ($arr[$i] == $value) {
            $result[0] = $i;
            $result[1] = $i;
            break;
        }
    }
    
    for ($j = $i; $j < count($arr) - 1; $j++) {
        if ($arr[$j] == $arr[$j + 1]) {
            $result[1] = $j + 1;
        }
        else {
            break;
        }
    }
    
    return $result;
}

$arr = array(1, 3, 4, 7, 7, 8, 8, 10, 11);
$value = 8;

$result = findStartingEndingPosition($arr, $value);

echo "start: " . $result[0] . "\n";
echo "end: " . $result[1] . "\n";



/*
run:

start: 5
end: 6

*/

 

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