Boshkash_Hates_CP's blog

2D-Prefix Sum
By Boshkash_Hates_CP, history, 4 months ago, In English

Hello , Recently i was trying to solve this problem 932B which was kinda tricky as it requires prefix sum to avoid TLE , it required 2d-prefix sum , so what's that and why i could need it , suggest some problems to get familiar with it.

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4 months ago, # |
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$$$p_{i,j}:=\sum_{x\le i,y\le j}a_{x,y}$$$

and

$$$p_{i,j}=p_{i-1,j}+p_{i,j-1}-p_{i-1,j-1}$$$

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4 months ago, # |
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