php面试题---杨辉三角

 

$n=10;//循环外层层数

$arr = '';

for($i=0;$i<=$n;$i++){

for($j=0;$j<=$i;$j++){

            if($j==0 || $j==$i){

                                     $arr[$i][$j] = 1;

                        }else{

                        $arr[$i][$j] = $arr[$i-1][$j] + $arr[$i-1][$j-1];

                       }

                       echo $arr[$i][$j]."\n";

           }

          echo "<br/>";

}