How to increase point in problem KALKI

general
1

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?

2

I simply used kruskal’s algo to get 70 points

3

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.