120 Degrees
Rotate that triangle.
Start file
1
9 2
8 3
7 6 5 4
End file
4
3 5
2 6
1 9 8 7
View Diff
1,4c1,4
< 1
< 9 2
< 8 3
< 7 6 5 4
---
> 4
> 3 5
> 2 6
> 1 9 8 7
Solutions by @jlaokan:
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