Question

How to implement the binary search algorithm in PHP

Answer 1

function binarySearch($array, $element, $low, $high) {
    while ($low <= $high) {
        $mid = $low + (int)(($high - $low) / 2);
 
        if ($array[$mid] == $element)
            return $mid;
 
        if ($array[$mid] < $element)
            $low = $mid + 1;
        else
            $high = $mid - 1;
    }
     
    return -1;
}
 
$array = array(3, 4, 6, 8, 9, 10, 12, 20, 27, 30, 31);
$number_to_find = 20;
 
$index = binarySearch($array, $number_to_find, 0, count($array));
         
if ($index == -1) 
    echo "Not found";
else
    echo "Found at index: " . $index;

 
 
 
/*
run:
 
Found at index: 7

*/

 

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