Didn't get the third condition. Can anyone explain?

Question

https://codeforces.com/contest/1325/problem/C

Answer 1

R_C
my java is poor😔
but the labels of nodes have no meaning.
Call them a, b, c if u want.

Answer 2

from node1 to node5 you have to walk edges 0 and 4.
lowest label of none walked edge is 1.
mex(1,5)=1

--> example of picture

Answer 3

Oma Falk
I'm using different approach.

First assigning label to leaves (0,1,2,..) then assigning labels to nodes left.

Answer 4

Why this code giving tle
https://code.sololearn.com/cbYV0pwfHt6d/?ref=app
My approach is first assigning numbers from 0 to all the leaves then the left node assigned

Answer 5

Oma Falk
Issue with Scanner class 😕. Used BufferedReader.. Got accepted