LeetCode 118 Pascal's Triangle

class Solution:
    def generate(self, numRows):
        """
        :type numRows: int
        :rtype: List[List[int]]
        """
        result = []
        for i in range(numRows):
            result.append([0] * (i + 1))
        for i in range(numRows):
            for j in range(i + 1):
                if j == 0 or j == i:
                    result[i][j] = 1
                else:
                    result[i][j] = result[i - 1][j - 1] + result[i - 1][j]
        return result