# What k lists should produce... (?)

• I'm not sure what the result for k lists should be. For

``````[1,2,3]
[4,5,6,7]
[8,9]
``````

I find it clear that it should be [1,4,8,5,2,6,9,7,3] because that looks like this:

``````[1,      2,      3]
[  4,  5,  6,  7  ]
[    8,      9    ]
``````

You can also compare it to the first zigzag problem and this nice explanation for it.

(Btw, kudos to WalkerIX for being first to point out that cycling isn't zigzagging.)

``````[1,2,3]
[4,5,6,7]
[8]
``````

I see two possibilities:

Keep zigzagging the original lists, producing [1,4,8,5,2,6,7,3]:

``````[1,      2,      3]
[  4,  5,  6,  7  ]
[    8       -    ]
``````

Keep zigzagging the remaining lists, producing [1,4,8,5,2,6,3,7]:

``````[1,      2,  3]
[  4,  5,  6,  7]
[    8]
``````

Thoughts?

• Oh, after reading your posts. I guess I may have misunderstood zigzag. In fact, my original answer to your first example is `[1, 4, 8, 2, 5, 9, 3, 6, 7]`:

``````[1,         2,         3]
[    4,         5,         6, 7]
[        8,         9]
``````

Oh, this is far too easier and certainly not zigzagging...

• Sorry for the ambiguous description in the problem statement.

For `k > 2` cases, the "zigzag" order is not clearly defined and is ambiguous. I have just updated the problem description. For your example, it should return `[1,4,8,2,5,9,3,6,7]`.

• But that's really not zigzag. Zigzag is going forth and back, forth and back, alternating directions, without jumping. Have a look at Wikipedia, Google images, or even the previous two zigzag problems right here on LeetCode. Is it too late to change the name of the problem?

• I agree zigzag is not the correct name. I can change the name. What name do you suggest, Stefan?

• I think "Round-Robin Iterator" would be good. Or "Cyclic Iterator". Though Round-Robin sounds nicer and already suggests that there are several things and that we're going through each of them ("cyclic" could refer to cycling through a single 1d-vector).

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