4 6
1 2 2
2 3 2
3 4 2
4 1 2
1 3 1
2 4 1
Cost: 4
Cost: 4
1:
why not 1>4(cost 2, minimum. Description says if transition between A > B is possible then B > A is possible too)
That gives answer: 2
2:1>3(cost 1) then 3>4(cost 2), 1+2=3
That gives answer: 3

Anyone mind explaining why its 4 and 4 in sample?

"choose the minimal possible set of trans-planet passages so that he could pass from any planet to any other one via those passages"

If you choose 1-3 and 3-4, you can't reach planet 2 from the other planets.