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Basic data structure algorithm_PHP tutorial
- WBOYOriginal
- 2016-07-13 10:52:33830browse
//--------------------
//Basic data structure algorithm
//--------------------
//Binary search (find an element in the array)
function bin_sch($array, $low, $high, $k){
if ($low <= $high){
$mid = intval(($low+$high)/2);
If ($array[$mid] == $k){
return $mid;
}elseif ($k < $array[$mid]){
return bin_sch($array, $low, $mid-1, $k);
return bin_sch($array, $mid+1, $high, $k);
}
Return -1;
}
//Sequential search (search for an element in the array)
function seq_sch($array, $n, $k){
$array[$n] = $k;
for($i=0; $i<$n; $i++){
If($array[$i]==$k){
break;
}
if ($i<$n){
return $i;
}else{
return -1;
}
}
//Deletion of linear table (implemented in array)
function delete_array_element($array, $i)
{
$len = count($array);
for ($j=$i; $j<$len; $j++){
$array[$j] = $array[$j+1];
}
array_pop($array);
return $array;
}
//Bubble sort (array sort)
function bubble_sort($array)
{
$count = count($array);
if ($count <= 0) return false;
for($i=0; $i<$count; $i++){
for($j=$count-1; $j>$i; $j--){
If ($array[$j] < $array[$j-1]){
}
}
return $array;
}
//Quick sort (array sort)
function quick_sort($array) {
If (count($array) <= 1) return $array;
$key = $array[0];
$left_arr = array();
$right_arr = array();
for ($i=1; $i
$left_arr[] = $array[$i];
else
$right_arr[] = $array[$i];
}
$left_arr = quick_sort($left_arr);
$right_arr = quick_sort($right_arr);
Return array_merge($left_arr, array($key), $right_arr);
}
//---------------------
// PHP built-in string function implementation
//---------------------
//String length
function strlen($str)
{
if ($str == '') return 0;
$count = 0;
If ($ Str [$ Count]! = Null) {
$count++;
continue;
}else{
break;
}
}
return $count;
}
//Intercept substring
function substr($str, $start, $length=NULL)
{
If ($str=='' || $start>strlen($str)) return;
If (($length!=NULL) && ($start>0) && ($length>strlen($str)-$start)) return;
If (($length!=NULL) && ($start<0) && ($length>strlen($str)+$start)) return;
If ($length == NULL) $length = (strlen($str) - $start);
if ($start < 0){
for ($i=(strlen($str)+$start); $i<(strlen($str)+$start+$length); $i++) {
}
}
if ($length > 0){
for ($i=$start; $i<($start+$length); $i++) {
}
}
if ($length < 0){
for ($i=$start; $i<(strlen($str)+$length); $i++) {
}
}
return $substr;
}
//String flip
function strrev($str)
{
if ($str == '') return 0;
for ($i=(strlen($str)-1); $i>=0; $i--){
$rev_str .= $str[$i];
}
return $rev_str;
}
//String comparison
function strcmp($s1, $s2)
{
If (strlen($s1) < strlen($s2)) return -1;
If (strlen($s1) > strlen($s2)) return 1;
for ($i=0; $i
continue;
}else{
return false;
}
}
return 0;
}
//Find string
function strstr($str, $substr)
{
$m = strlen($str);
$n = strlen($substr);
if ($m < $n) return false;
for ($i=0; $i<=($m-$n+1); $i++){
$sub = substr($str, $i, $n);
if (strcmp($sub, $substr) == 0) return $i;
}
return false;
}
//字符串替换
function str_replace($substr, $newsubstr, $str)
{
$m = strlen($str);
$n = strlen($substr);
$x = strlen($newsubstr);
if (strchr($str, $substr) == false) return false;
for ($i=0; $i<=($m-$n+1); $i++){
$i = strchr($str, $substr);
$str = str_delete($str, $i, $n);
$str = str_insert($str, $i, $newstr);
}
return $str;
}
//--------------------
// 自实现字符串处理函数
//--------------------
//插入一段字符串
function str_insert($str, $i, $substr)
{
for($j=0; $j<$i; $j++){
$startstr .= $str[$j];
}
for ($j=$i; $j
}
$str = ($startstr . $substr . $laststr);
return $str;
}
//删除一段字符串
function str_delete($str, $i, $j)
{
for ($c=0; $c<$i; $c++){
$startstr .= $str[$c];
}
for ($c=($i+$j); $c
}
$str = ($startstr . $laststr);
return $str;
}
//复制字符串
function strcpy($s1, $s2)
{
if (strlen($s1)==NULL || !isset($s2)) return;
for ($i=0; $i
}
return $s2;
}
//连接字符串
function strcat($s1, $s2)
{
if (!isset($s1) || !isset($s2)) return;
$newstr = $s1;
for($i=0; $i
}
return $newsstr;
}
//简单编码函数（与php_decode函数对应）
function php_encode($str)
{
if ($str=='' && strlen($str)>128) return false;
for($i=0; $i
if ($c>31 && $c<107) $c += 20;
if ($c>106 && $c<127) $c -= 75;
$word = chr($c);
$s .= $word;
}
return $s;
}
//简单解码函数（与php_encode函数对应）
function php_decode($str)
{
if ($str=='' && strlen($str)>128) return false;
for($i=0; $i
if ($c>106 && $c<127) $c = $c-20;
if ($c>31 && $c<107) $c = $c+75;
$word = chr($c);
$s .= $word;
}
return $s;
}
//简单加密函数（与php_decrypt函数对应）
function php_encrypt($str)
{
$encrypt_key = 'abcdefghijklmnopqrstuvwxyz1234567890';
$decrypt_key = 'ngzqtcobmuhelkpdawxfyivrsj2468021359';
if (strlen($str) == 0) return false;
for ($i=0; $i
$enstr .= $decrypt_key[$j];
break;
}
}
}
return $enstr;
}
//简单解密函数（与php_encrypt函数对应）
function php_decrypt($str)
{
$encrypt_key = 'abcdefghijklmnopqrstuvwxyz1234567890';
$decrypt_key = 'ngzqtcobmuhelkpdawxfyivrsj2468021359';
if (strlen($str) == 0) return false;
for ($i=0; $i
$enstr .= $encrypt_key[$j];
break;
}
}
}
return $enstr;
}
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