按数量级递增排列，常见的时间复杂度有：常数阶O(1),对数阶O(log2n),线性阶O(n),线性对数阶O(nlog2n),平方阶O(n2)，立方阶O(n3)
代码如下:
//二分查找O(log2n)
function erfen($a,$l,$h,$f){
if($l >$h){ return false;}
$m = intval(($l+$h)/2);
if ($a[$m] == $f){
return $m;
}elseif ($f < $a[$m]){
return erfen($a, $l, $m-1, $f);
}else{
return erfen($a, $m+1, $h, $f);
}
}
$a = array(1,12,23,67,88,100);
var_dump(erfen($a,0,5,1));
//遍历树O(log2n)
function bianli($p){
$a = array();
foreach (glob($p.'/*') as $f){
if(is_dir($f)){
$a = array_merge($a,bianli($f));
}else{
$a[] = $f;
}
}
return $a;
}
//阶乘O(log2n)
function jc($n){
if($n<=1){
return 1;
}else{
return $n*jc($n-1);
}
}
//快速查找 O(n *log2(n))
function kuaisu($a){
$c = count($a);
if($c <= 1){return $a;}
$l = $r = array();
for ($i=1;$i<$c;$i++){
if($a[$i] < $a[0]){
$l[] = $a[$i];
}else{
$r[] = $a[$i];
}
}
$l = kuaisu($l);
$r = kuaisu($r);
return array_merge($l,array($a[0]),$r);
}
//插入排序 O(N*N)
function charu($a){
$c = count($a);
for($i=1;$i<$c;$i++){
$t = $a[$i];
for($j=$i;$j>0 && $a[$j-1]>$t;$j--){
$a[$j] = $a[$j-1];
}
$a[$j] = $t;
}
return $a;
}
//选择排序O(N*N)
function xuanze($a){
$c = count($a);
for($i=0;$i<$c;$i++){
for ($j=$i+1;$j<$c;$j++){
if($a[$i]>$a[$j]){
