A big equilateral triangle is made up of smaller equilateral triangles. The relation is for n order of the bigger triangle, the number of inner triangles are n^2. Example of such a triangle with n = 3.
Now for the given triangles, we mark every vertex, except one, with value of 1, and the remaining one being -1. This one anomaly vertex could be any vertex. In our given example of n being 3, there are 10 vertices, A being one of them. Now at each step, we select one small triangle and reverse the values of all its vertices i.e. 1 becomes -1 and vice versa.
Is it possible to transform all vertex to have value 1?