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1325C
By vinu_93, history, 5 years ago, In English

i cant understand the problem. https://mirror.codeforces.com/problemset/problem/1325/C

can someone help me please

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5 years ago, # |
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Solution

  • You have a tree with n vertices, so n-1 edges.
  • Mark all the edges with numbers from 0 to n-2.
  • Take any pair of vertices and write down the numbers on the edges in the shortest path between them.
  • Find the MEX of this array.

If you understand how MEX works, the problem is simple. The MEX of any path that doesn't contain the edge labeled 0 is 0. Find a vertex which has more than 3 edges, and mark them 0, 1, 2. Mark the remaining edges randomly. This ensures that the maximum MEX is 2.

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