|
error_reporting(E_ALL);
ini_set("display_errors", 1);
//避免超时
set_time_limit(0);
$t1=microtime();
function isPlalindrome($num){
$str="$num";
$len=strlen($num);
$k = intval($len/2) 1;//获取中间位数
for($j=0;$j<$k;$j ){
if($str{$j}!=$str{$len-1-$j}){
return false;
}
}
return true;
}
function showPlalindrome($min,$max){
//因为要计算在$min,$max间的回文数且其自身平方根也是回文数
//所以相当于求一sqrt($min)~sqrt($max)间数
//其平方在$min~$max间也是回文数
//$min~$max是连续正整数，所以可以这样缩小很多计算量，否则……
$start=sqrt($min);
$end=sqrt($max);
for($i=$start;$i<$end;$i ){
if(isPlalindrome($i) &&isPlalindrome($n=$i*$i) ){
echo $n."
";
}
}
}
showPlalindrome(1,100000000000000);
$t2=microtime();
$starttime = explode(" ",$t1);
$endtime = explode(" ",$t2);
$totaltime = $endtime[0]-$starttime[0] $endtime[1]-$starttime[1];
$timecost = sprintf("%s",$totaltime);
echo "页面运行时间: $timecost 秒";
?>
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