from typing import List

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

    return ret

print(generate(5))