A tough loop in a contest

Question: Input N = 4
          Output:
                 1
                 0 1
                 1 0 1
                 0 1 0 1

I tried many things but every time I failed.

Apart from this stupid wrong solution I tried many fancy stuff and failed in the end.
What part of my C knowledge is weak?

If you were given this question how would you solve it?

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