leetcode 杨辉三角取某一行

Given a non-negative index k where k ≤ 33, return the kth index row of the Pascal's triangle.

Note that the row index starts from 0.

In Pascal's triangle, each number is the sum of the two numbers directly above it.

Example:

Input: 3
Output: [1,3,3,1]

 function getRow($rowIndex) {
        $numRows=$rowIndex+1;
        $re=[];
        for($i=1;$i<=$numRows;$i++){
          if($i==1){
              $num=[1];
          }else if($i==2){
              $num=[1,1];
          }else{
              foreach($num as $k=>$v){
                  $n=$k+1;
                  if(isset($num[$n])){
                       $mid[$k]=$v+$num[$n]; 
                  }
              }
                 $num=$mid;
                     array_push($num,1);
                     array_unshift($num,1);
          }
            array_push($re,$num);
        }
        return $re[$rowIndex];
    }