Light three purple, three yellow, three green and three blue festive bulbs in the grid so that the bulbs of the same color lie in the corners of an equilateral triangle and all four resulting triangles are of the different size. Four bulbs, each of different color, are already lit in the third row as shown. Only two bulbs of each color are left to be lit, but where?
Click an empty circle till the required color bulb appears. Every fifth click returns the circle to its initial state.