119. Pascal's Triangle II - LeetCode Solution

class Solution:
    def getRow(self, rowIndex: int) -> List[int]:
        a = [[1], [1,1]]
        
        if rowIndex <=1:
            return a[rowIndex]
        
        for i in range(1, rowIndex):
            b = [1]
            
            for j in range(len(a[i])-1):
                b.append(a[i][j]+ a[i][j+1] )
                
            b.append(1)
            a.append(b)
            
        return a[rowIndex]