Basic data structure and PHP built-in function implementation _php Tutorial

Two-part lookup function

Binary lookup (Find an element in an 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, $k);
}else{
Return Bin_sch ($array, $mid +1, $high, $k);
}
}
return-1;
}

Implementation of Sequential Lookup function

Order 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;
}
}
Implementation of the deletion function of linear table

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;
}
The implementation of the bubbling sort function:

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;
}
Fast sorting function implementation

Quick sort (Array sort)
function Quicksort ($array) {
if (count ($array) <= 1) return $array;

$key = $array [0];
$left _arr = Array ();
$right _arr = Array ();

for ($i =1; $i
if ($array [$i] <= $key)
$left _arr[] = $array [$i];
Else
$right _arr[] = $array [$i];
}

$left _arr = quicksort ($left _arr);
$right _arr = quicksort ($right _arr);

Return Array_merge ($left _arr, Array ($key), $right _arr);
}

PHP built-in string function implementation

//------------------------
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;
}

Implementation of truncated substring function


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 + +) {

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http://www.bkjia.com/PHPjc/364046.html www.bkjia.com true http://www.bkjia.com/PHPjc/364046.html techarticle binary Lookup Function//two-point lookup (Find an element in an array) function Bin_sch ($array, $low, $high, $k) {if ($low = $high) {$mid = Intval (($low + $high)/2); if ($array [$mid] = = $ ...

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