I participated in Codeforces Round 907 (Div. 2). I believe it could be the first time I was late for a Codeforces Round but still participated in it; however, I solved all problems. The round featured a lot of ideas, which were pretty standard, but it still was kinda nice to discover them here.
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approach for f with euler tour and lazy Propagation with seg tree is giving tle on tc 22. here is the code- https://codeforces.net/contest/1891/submission/230589277
Fenwick tree is much faster than a regural segment tree, and segment tree without lazy propagation can me much faster than the one with lazy propagation. Also the up-to-bottom implementation of segment tree can be substantially slower than the bottom-to-top one.
Also note that in your implementation of Euler tour each vertex is put twice in the array. This is not needed, however: one time (either at the beginning or at the end of the
dfsprocedure) is enough.So I definitely feel for you, but I have to admit there is enough room for optimization in your solution. My approach gets OK in 295 ms: 230557194. If I were a problemsetter, I would try to loosen TL as much as possible, and your solution would probably get OK as well.
P.S. The editorial proposes the same approach I used.
thanks for this knowledge.I don't know how to use fenwick tree,i will try to learn in few days. I know i can optimize my code further and my changing map to unordered_map i got ac.