用Python，输出7行的杨辉三角

可以使用两个列表来保存杨辉三角上一行和当前行的元素，然后根据上一行的元素计算当前行的元素。以下是实现代码：

def generate_pascal_triangle(num_rows):
    triangle = []
    for i in range(num_rows):
        row = [1] * (i + 1)
        for j in range(1, i):
            row[j] = triangle[i-1][j-1] + triangle[i-1][j]
        triangle.append(row)
    return triangle

# 输出7行的杨辉三角
triangle = generate_pascal_triangle(7)
for row in triangle:
    print(row)

输出结果：

[1]
[1, 1]
[1, 2, 1]
[1, 3, 3, 1]
[1, 4, 6, 4, 1]
[1, 5, 10, 10, 5, 1]
[1, 6, 15, 20, 15, 6, 1]