src/problems/php/easy/binary_search.php

<?php

/**
 * Binary Search
 * @link https://leetcode.com/problems/binary-search
 *
 * Approach:
 * Just implement Binary Search algorithm
 *
 * Time complexity - O(log n)
 * Space complexity - O(1)
 */
function search($nums, $target) {
    list($first, $last) = [0, count($nums) - 1];

    while ($first <= $last) {
        $middle = floor(($first + $last) / 2);

        if ($nums[$middle] === $target) {
            return $middle;
        }

        if ($nums[$middle] < $target) {
            $first = $middle + 1;
        } else {
            $last = $middle - 1;
        }
    }

    return -1;
}