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Need help in problem E — Greedy Shopping
By hurt_FOR_heart, history, 3 years ago, In English

Hello, at problem E last contest I have do segment tree and binary search which reach a good complexity O((n+q)log(maxY)log(n)) but i dont know why It just give me a TLE judgement on test 18 Maybe my poor implementation ? Or there's some infinite loop ? Or I just make a wrong calculation in complexity ? I still cant find my mistake so I hope u guy could help me. Here is my code: https://codeforces.com/contest/1440/submission/98824111 Thanks in advance.

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3 years ago, # |
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I think your type 2 queries might be $$$\mathcal O(\log^2 n \log y)$$$.

while (pos <= n): This while loop executes $$$\log y$$$ times, once for each continuous segment.

first_small(pos,y), Get_pos(pos,y): Both of these seem to be $$$\log^2 n$$$ operations. They each have a $$$\log n$$$ while loop and call Get(1,1,n,pos,m) or Get(1,1,n,m,m) at each iteration, which is another $$$\log n$$$ operation.

To remedy this, replace Get(1,1,n,pos,m) or Get(1,1,n,m,m) by simply checking the sum of the subtrees in $$$\mathcal O(1)$$$ when deciding which children to traverse to.

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    3 years ago, # ^ |
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    i got it,thank you so much for helping me. But i have use some technique called walk on tree. Is it what you mean ?

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      3 years ago, # ^ |
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      Yes, I was describing walking down the tree in my last sentence :)

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