帕斯卡三角形二维数组格式化打印输出

def generate_pascals_triangle(num_rows):
    triangle = []
    for row_num in range(num_rows):
        # The first and last row elements are always 1.
        row = [None for _ in range(row_num + 1)]
        row[0], row[-1] = 1, 1
        # Each triangle element is equal to the sum of the elements above-and-to-the-left and above-and-to-the-right.
        for j in range(1, len(row) - 1):
            row[j] = triangle[row_num - 1][j - 1] + triangle[row_num - 1][j]
        triangle.append(row)
    return triangle

def print_pascals_triangle(triangle):
    max_width = len(" ".join(map(str, triangle[-1])))
    for row in triangle:
        print(" ".join(map(str, row)).center(max_width))

# Generate and print Pascal's Triangle
num_rows = 10
triangle = generate_pascals_triangle(num_rows)
print_pascals_triangle(triangle)