C:\test>junk
[
    [1],
    [2, 3],
    [4, 5, 6],
    [7, 8, 9, 10]
]
[
    [1, 0, 0, 0],
    [2, 3, 0, 0],
    [4, 5, 6, 0],
    [7, 8, 9, 10]
]

[
    [1],
    [2, 3],
    [4, 5, 6],
    [7, 8, 9, 10],
    [11, 12, 13, 14, 15]
]

[
    [1, 0, 0, 0, 0],
    [2, 3, 0, 0, 0],
    [4, 5, 6, 0, 0],
    [7, 8, 9, 10, 0],
    [11, 12, 13, 14, 15]
]