Anyone Ever Seen a Zig Zag Pattern like this?

A friend asked me to remake this hat for her, but I’ve never seen anything like it. It is a SO brand beanie. It is not knit on the round, it is darned in the back, which is the only place it is darned, beside the very top. That means it is one continuous piece. I can’t figure out how they made it? Anyone have experience with it? I don’t have experience with crocheting, could it be that?

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Very nice pattern, definitely knitting. It’s made by lines of increases and decreases as you go up the hat. It’s similar to these afghans although the increases that leave eyelets aren’t used in the hat: