kindly
d
o
n
t
see
comments

for
solving this
you should know
famous
graph
algorithms
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still
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take 1 as start node..

BFS + BFS ! .. AC in one go .. :)

getting tle

That's not true either. I think what you mean to say is that it implies that if the test data is not wrong, then it is incomplete. (This is ignoring the possibility of a faulty judge, for simplicity.)

Weak test data is of course a valid quality concern. There are various factors to consider when it comes to that. I don't want to go into details at the moment, but consider some examples of weakness:

1) test data allows a greedy approach to pass, even though that approach will not always produce correct answers.
2) constraints state n <= 10^8, but in the test data we actually have n <= 10^6.
3) test data is missing the case n=0.
4) perfect squares are a tricky case, but they are not included in the test data.
5) test data was generated randomly according to uniform distribution, leading to a situation where 99% of cases can be solved in a trivial way while the other 1% are hard.

I think it's important to consider the nature and severity of the weakness before changing the test data or requesting for it to be changed. Also, consider that many problems were published many years ago, and the problem setter may be inactive. In some cases, it could be a good option to create a new and improved version of the problem instead of trying to modify the old one.