class Solution:
    def generate(self, numRows: int) -> List[List[int]]:
        res = []
        for n in range(numRows):
            row = [1]
            val = 1
            for k in range(1, n + 1):
                val = val * (n - k + 1) // k
                row.append(val)
            res.append(row)
        return res

class Solution:
    def generate(self, numRows: int) -> List[List[int]]:
        res = [[1]]

        for i in range(numRows - 1):
            temp = [0] + res[-1] + [0]
            row = []
            for j in range(len(res[-1]) + 1):
                row.append(temp[j] + temp[j + 1])
            res.append(row)
        return res

class Solution:
    def generate(self, numRows: int) -> List[List[int]]:
        res = [[1] * (i + 1) for i in range(numRows)]
        for i in range(2, numRows):
            for j in range(1, i):
                res[i][j] = res[i - 1][j - 1] + res[i - 1][j]
        return res