Old text reorganization: data structure and string processing code collation

Data | structure | string

Sorting out some of the previously written algorithms and string processing functions, things have no use, just to learn.

Author:heiyeluren
Blog:http://blog.csdn.net/heiyeshuwu
Date:2006-06-10 23:50

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//--------------------
Basic Data structure algorithm
//--------------------

//Two-point lookup (Find an element in an array)
function Bin_sch ($array, $low, $high, $k) { 
    if ($low <= $high) {& nbsp
        $mid = Intval (($low + $high)/2); 
         if ($array [$mid] = = $k) { 
             return $mid; 
       }elseif ($k < $array [$mid]) { 
            return Bin_sch ($array, $low, $mid-1, $k); 
       }else{ 
             return Bin_sch ($array, $mid +1, $high, $k); 
       }& nbsp
   } 
    return-1; 
} 

//Sequential lookup (find an element in an 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 tables (implemented in arrays)
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]) {
$tmp = $array [$j];
$array [$j] = $array [$j-1];
$array [$j-1] = $tmp;
}
}
}
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; $i <count ($array); $i + +) {
if ($array [$i] <= $key)
$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;

$count = 0;
while (1) {
if ($str [$count]!= NULL) {
$count + +;
Continue
}else{
Break
}
}
return $count;
}

To intercept a child string
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 + +) {
$substr. = $str [$i];
}
}

        if ($length > 0) {
                 for ($i = $start; $i < ($start + $length); $i + +) {
                          $substr. = $str [$i];
               }
       }

        if ($length < 0) {
                 for ($i = $start; $i < (strlen ($STR) + $length); $i + +) {
                          $substr. = $str [$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 comparisons
function strcmp ($s 1, $s 2)
{
if (strlen ($s 1) < strlen ($s 2)) return-1;
if (strlen ($s 1) > strlen ($s 2)) return 1;

        for ($i =0 $i <strlen ($s 1); $i + +) {
                 if ($s 1[$i] = = $s 2[$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;
}

String substitution
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;
}

//--------------------
Self-Implementation String handler function
//--------------------

Insert a section of string
function Str_insert ($str, $i, $SUBSTR)
{
for ($j =0; $j < $i; $j + +) {
$startstr. = $str [$j];
}
for ($j = $i; $j <strlen ($STR); $j + +) {
$laststr. = $str [$j];
}
$str = ($startstr. $substr. $laststr);

return $str;
}

Delete a section of a string
function Str_delete ($str, $i, $j)
{
for ($c =0; $c < $i; $c + +) {
$startstr. = $str [$c];
}
for ($c = ($i + $j); $c <strlen ($STR); $c + +) {
$laststr. = $str [$c];
}
$str = ($startstr. $laststr);

return $str;
}

Copy string
function strcpy ($s 1, $s 2)
{
if (strlen ($s 1) ==null | |!isset ($s 2)) return;

For ($i =0 $i <strlen ($s 1); $i + +) {
$s 2[] = $s 1[$i];
}
return $s 2;
}

Connection string
function strcat ($s 1, $s 2)
{
if (!isset ($s 1) | | |!isset ($s 2)) return;
$newstr = $s 1;
for ($i =0; $i <count ($s); $i + +) {
$newstr. = $st [$i];
}
return $newsstr;
}

Simple encoding function (corresponding to the Php_decode function)
function Php_encode ($STR)
{
if ($str = = ' && strlen ($STR) >128) return false;

for ($i =0; $i <strlen ($STR); $i + +) {
$c = Ord ($str [$i]);
if ($c >31 && $c <107) $c + + 20;
if ($c >106 && $c <127) $c-= 75;
$word = Chr ($c);
$s. = $word;
}

return $s;
}

Simple decoding function (corresponding to the Php_encode function)
function Php_decode ($STR)
{
if ($str = = ' && strlen ($STR) >128) return false;

for ($i =0; $i <strlen ($STR); $i + +) {
$c = Ord ($word);
if ($c >106 && $c <127) $c = $c-20;
if ($c >31 && $c <107) $c = $c +75;
$word = Chr ($c);
$s. = $word;
}

return $s;
}

Simple cryptographic functions (corresponding to the Php_decrypt function)
function Php_encrypt ($STR)
{
$encrypt _key = ' abcdefghijklmnopqrstuvwxyz1234567890 ';
$decrypt _key = ' ngzqtcobmuhelkpdawxfyivrsj2468021359 ';

if (strlen ($str) = = 0) return false;

for ($i =0; $i <strlen ($STR); $i + +) {
For ($j =0 $j <strlen ($encrypt _key); $j + +) {
if ($str [$i] = = $encrypt _key[$j]) {
$enstr. = $decrypt _key[$j];
Break
}
}
}

return $enstr;
}

Simple decryption function (corresponding to the Php_encrypt function)
function Php_decrypt ($STR)
{
$encrypt _key = ' abcdefghijklmnopqrstuvwxyz1234567890 ';
$decrypt _key = ' ngzqtcobmuhelkpdawxfyivrsj2468021359 ';

if (strlen ($str) = = 0) return false;

for ($i =0; $i <strlen ($STR); $i + +) {
For ($j =0 $j <strlen ($decrypt _key); $j + +) {
if ($str [$i] = = $decrypt _key[$j]) {
$enstr. = $encrypt _key[$j];
Break
}
}
}

return $enstr;
}

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