How to solve this question using BIT?
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How to solve this question using BIT?
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It can be solved using dynamic programming. First use coordinate compression to get the values from 1...N Let dp[i][j] be number of subsequences of length j ending with i. Then, dp[i][j]=dp[i-1][j-1]+dp[i-2][j-1]+.....+dp[1][j-1];
This will take O(N*N*K) time.
Since a dp[i][j] is a cumulative sum of 0....i-1 we can use BIT for this purpose. We will have to make to make K BITs so that a particular state can be answered in O(logn) time. Complexity(O(N*K*logN))
There is a copy of this problem: 597C - Subsequences, my solution using BIT: 15007060, Deemo's one: 14269844.
for more explanation https://www.geeksforgeeks.org/count-number-increasing-subsequences-size-k/
Thank you so much bro
its ok brooo !!