IOI 2011

Tropical Garden

In garden, Somhed love walking through beautiful trail. (Number on the trail is beauty ranking: 1 means this trail is the most beautiful.) At each intersection Somhed will choose to walk through
  • The 1st beautiful trail, in general.
  • The 2nd beautiful trail, if the 1st one is the most recent he passed and there are more than one ways at the intersection.
If Somhed has walked through 10 trails and stop at green intersection, find all the intersections he may start.
Your Task
  1. Click at some intersection and click .
  2. It will reveal whether the choosen intersection is one of possible starting intersection.
  3. Click , and find out whether you Win or Lose. Aha!
Competitors' Task
  • Calculate the number of possible starting intersection.
  • Garden is super large: upto 150,000 intersections and trails.
  • Somhed may have walked through 1,000,000,000 trails, and, some more burdensome stuffs.
Level 1
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