[LeetCode] 118.Pascal's Triangle

很简单的杨辉三角问题，时间复杂度是O(N), 空间复杂度是O(1)

class Solution:
    def generate(self, numRows: int) -> List[List[int]]:
        if numRows == 0:
            return []
        
        result = [[1]]
        for row in range(1,numRows):
            new_row = [1]
            for col in range(len(result[row - 1]) - 1): 
                new_row.append(result[row - 1][col] + result[row - 1][col + 1])
            new_row.append(1)
            result.append(new_row)
        return result