class Solution:
    def generate(self, numRows: int) -> List[List[int]]:
        res = []
        for i in range(numRows):
            t = [1 if j == 0 or j == i else 0 for j in range(i + 1)]
            for j in range(1, i):
                t[j] = res[i - 1][j - 1] + res[i - 1][j]
            res.append(t)
        return res