二分查找 * 思路分析：数组中间的值floor((low+top)/2) * 先取数组中间的值floor((low+top)/2)然后通过与所需查找的数字进行比较， * 若比中间值大则将首值替换为中间位置下一个位置，继续第一步的操作； * 若比中间值小，则将尾值替换为中间位置上一个位置，继续第一步操作 * 重复第二步操作直至找出目标数字 ~~~ function BinaryQuery(array $container, $search) { $top = count($container); $low = 0; while ($low <= $top) { $mid = intval(floor(($low + $top) / 2)); if (!isset($container[$mid])) { return '没找着哦'; } if ($container[$mid] == $search) { return $mid; } $container[$mid] < $search && $low = $mid + 1; $container[$mid] > $search && $top = $mid - 1; } } ~~~ 递归版 二分查找 ~~~ function BinaryQueryRecursive(array $container, $search, $low = 0, $top = 'default') { $top == 'default' && $top = count($container); if ($low <= $top) { $mid = intval(floor($low + $top) / 2); if (!isset($container[$mid])) { return '没找着哦'; } if ($container[$mid] == $search) { return $mid; } if ($container[$mid] < $search) { return BinaryQueryRecursive($container, $search, $mid + 1, $top); } else { return BinaryQueryRecursive($container, $search, $low, $mid - 1); } } } ~~~