Difficulty
\(hard\)
The meaning of problems
Italian official Chinese title
practice
Set \ (G = (V, E ) \)
is defined. 1 : \ (M (G) \) of \ (G \) minimum point coverage
defined 2 : \ (ANS (G) \) of \ (G \) the meaning of the questions the answer, regardless of the boatman
Conclusion. 1 : \ (M (G) \ Le ANS (G) \)
The first at least be taken \ (M (G) \) th
Conclusion 2 : \ (ANS (G) \ Le M (G) + 1'd \)
I.e. with \ (M (G) +1 \ ) positions must be able to take all of: the first tape \ (M (G) \) , which is fixed on the boat, each time the left bank and a discharge point into the boat again to the right bank
Conclusion. 3 : \ (G \) is daisy FIG \ (ans (G) = M (G) = 1 \)
Obviously, not elaborate
Conclusion. 4 : \ (G \) when not daisy FIG \ (ans (G) = M (G) \)
The first band \ (M (G) \) , apparently \ (M (G) \ GE 2 \) , consider \ (M (G) \) point represented by two different focus points \ (u, v \ ) , we \ (V \) in the right bank and \ (U \) not adjacent (V \) \ Since the same time; point adjacent band on the right bank \ (u, v \) phase at most adjacent point \ (1 \) a, after release tape \ (V \) , at the interface with the left bank \ (V \) in the left bank, to bring it up to a point, if not not belt; then we will empty out of a position of the ship, the \ (G \ backslash M (G ) \) to fit in to the right bank
Then the board is