function binarySearch($array, $key, $low, $high)
{
if ($low > $high) {
return -1;
}
$middle = (int) (($high + $low) / 2);
if ($array[$middle] == $key) {
return $middle;
} elseif ($array[$middle] > $key) {
return binarySearch($array, $key, $low, $middle - 1);
} elseif ($array[$middle] < $key) {
return binarySearch($array, $key, $middle + 1, $high);
}
}
function array2DBunarysearch($arr2D, $needle)
{
$len = count($arr2D);
$currentMin;
for ($i = 0; $i < $len; $i++) {
$currentMin = $arr2D[$i][0];
if ($currentMin > $needle) {
continue;
}
$j = binarySearch($arr2D[$i], $needle, 0, count($arr2D[$i]) - 1);
if ($j != -1) {
return $i . ' ' . $j;
}
}
}
function binarySearch($arr, $findVal, $leftIndext, $rightIndext)
{
if ($rightIndext < $leftIndext) {
echo "查询不到";
return;
}
$middleIndext = round(($leftIndext + $rightIndext) / 2);
if ($findVal < $arr[$middleIndext]) {
binarySearch($arr, $findVal, $leftIndext, $middleIndext - 1);
} else {
if ($findVal > $arr[$middleIndext]) {
binarySearch($arr, $findVal, $middleIndext + 1, $rightIndext);
} else {
echo "已查询到了 {$middleIndext}";
}
}
}
function binarySearch($arr, $n, $m1, $n1, $m2, $n2)
{
$start_row = $m1;
$start_col = $n1;
$end_row = $m2;
$end_col = $n2;
$i = intval(($m1 + $m2) / 2);
$j = intval(($n1 + $n2) / 2);
if (!isset($arr)) {
return false;
}
if ($n < $arr[$m1][$n1] || $n > $arr[$m2][$n2]) {
return false;
} elseif ($n == $arr[$m1][$n1] || $n == $arr[$m2][$n2]) {
return true;
}
while (($i != $m1 || $j != $n1) && ($i != $m2 || $j != $n2)) {
if ($n == $arr[$i][$j]) {
return true;
} elseif ($n < $arr[$i][$j]) {
$m2 = $i;
$n2 = $j;
$i = intval(($i + $m1) / 2);
$j = intval(($j + $n1) / 2);
} else {
$m1 = $i;
$n1 = $j;
$i = intval(($i + $m2) / 2);
$j = intval(($j + $n2) / 2);
}
}
//search right
if ($i < $end_row) {
$left_result = binarySearch($arr, $n, $i + 1, $start_col, $end_row, $j);
}
//search left
if ($j < $end_col) {
$right_result = binarySearch($arr, $n, $start_row, $j + 1, $i, $end_col);
}
if ($left_result || $right_result) {
return true;
} else {
return false;
}
}
function binarySearch($arr, $findVal, $leftIndex, $rightIndex)
{
if ($rightIndex < $leftIndex) {
echo "查询不到";
return;
}
$middleIndext = round(($leftIndex + $rightIndex) / 2);
if ($findVal < $arr[$middleIndext]) {
//函数参数位置不能换 并且参数不能写错了
binarySearch($arr, $findVal, $leftIndex, $middleIndext - 1);
} else {
if ($findVal > $arr[$middleIndext]) {
binarySearch($arr, $findVal, $middleIndext + 1, $rightIndex);
} else {
echo "已查询到了 {$middleIndext}";
}
}
}
function binarySearch($arr, $val, $start, $end)
{
$num = $end - $start;
if ($num > 1) {
$average = ceil($num / 2);
if ($arr[$start + $average] == $val) {
return $start + $average;
}
if ($arr[$start + $average] > $val) {
return binarySearch($arr, $val, $start, $start + $average - 1);
}
return binarySearch($arr, $val, $start + $average, $end);
}
if ($arr[$end] >= $val && $arr[$start] < $val) {
return $end;
}
return $start;
}
function check_whitelist($list, &$snum)
{
if (empty($list)) {
return array();
}
$file = dirname(__FILE__) . '/AIBOLIT-WHITELIST.db';
$snum = max(0, @filesize($file) - 1024) / 20;
echo "\nLoaded " . ceil($snum) . " known files\n";
sort($list);
$hash = reset($list);
$fp = @fopen($file, 'rb');
if (false === $fp) {
return array();
}
$header = unpack('V256', fread($fp, 1024));
$result = array();
foreach ($header as $chunk_id => $chunk_size) {
if ($chunk_size > 0) {
$str = fread($fp, $chunk_size);
do {
$raw = pack("H*", $hash);
$id = ord($raw[0]) + 1;
if ($chunk_id == $id and binarySearch($str, $raw)) {
$result[] = $hash;
}
} while ($chunk_id >= $id and $hash = next($list));
if ($hash === false) {
break;
}
}
}
fclose($fp);
return $result;
}
return $mid;
}
#中元素比目标大,查找左部
if ($arr[$mid] > $target) {
$high = $mid - 1;
}
#重元素比目标小,查找右部
if ($arr[$mid] < $target) {
$low = $mid + 1;
}
}
#查找失败
return false;
}
$arr = array(1, 3, 5, 7, 9, 11);
$inx = binarySearch($arr, 1);
var_dump($inx);
function php_explode($delim, $str)
{
if (!$delim) {
return false;
}
$delim = strval($delim);
$str = strval($str);
if (!$delim || !$str) {
return false;
}
$delim_len = strlen($delim);
$str_len = strlen($str);
if ($delim_len > $str_len) {
return false;
*/
/**
* @param $x
* @param array $list
*
* @return float|int
*/
function binarySearch($x, array $list)
{
$left = 0;
$right = count($list) - 1;
while ($left <= $right) {
$mid = floor(($left + $right) / 2);
echo $mid . ',';
if ($list[$mid] == $x) {
return $mid;
} elseif ($list[$mid] > $x) {
$right = $mid - 1;
} elseif ($list[$mid] < $x) {
$left = $mid + 1;
}
}
return -1;
}
$arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13];
$find = 8;
var_dump($arr);
echo 'We look for number:' . $find . '<br>';
echo '<b>Binary Search with iteration: </b><br>';
echo '<br>' . binarySearch($find, $arr);
function binarySearch(&$arr, $findVal, $left, $right)
{
if ($left > $right) {
return;
}
$midIndex = round(($left + $right) / 2);
if ($arr[$midIndex] > $findVal) {
binarySearch($arr, $findVal, $left, $midIndex - 1);
} else {
if ($arr[$midIndex] < $findVal) {
binarySearch($arr, $findVal, $midIndex + 1, $right);
} else {
return $midIndex;
}
}
}
/**
* Created by PhpStorm.
* User: liulei
* Date: 16/9/21
* Time: 下午11:50
*/
function binarySearch($arr = [], $target)
{
$length = count($arr);
$low = 0;
$high = $length - 1;
while ($low <= $high) {
$mid = floor(($low + $high) / 2);
if ($arr[$mid] == $target) {
return '元素的位置是:' . $mid;
}
if ($arr[$mid] > $target) {
$high = $mid - 1;
}
if ($arr[$mid] < $target) {
$low = $mid + 1;
}
}
return 'Not Found';
}
$arr = [1, 3, 5, 7, 9, 10, 15, 18];
echo binarySearch($arr, 9) . PHP_EOL;
echo binarySearch($arr, 18) . PHP_EOL;
echo binarySearch($arr, 14);
