How to increase point in problem KALKI

Hi, I’m still not understand how to increase my point in the problem KALKI and the others have same type in the contest. Someone can help me to explain about this?

I simply used kruskal’s algo to get 70 points

Thanks you, I used that algorithm but I don’t know what we must optimized for this problems type. I want to know what we must optimized to get the higher point.