Photoshoot
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Farmer John is looking at his cows in a magical field and wants to take pictures
of subsets of his cows.
The field can be seen as a \(N \times N\) grid \((1 \leq N \leq 500)\), with a
single stationary cow at each location. Farmer John's camera is capable of
taking a picture of any \(K \times K\) square that is part of the field
\((1 \leq K \leq \min(N, 25))\).
At all times, each cow has a beauty value between \(0\) and \(10^6\). The
attractiveness index of a picture is the sum of the beauty values of the cows
contained in the picture.
The beauty value for every cow starts out as \(0\), so the attractiveness index of
any picture in the beginning is \(0\).
At \(Q\) times \((1 \leq Q \leq 3\cdot 10^{4})\), the beauty of a single cow will
increase by a positive integer due to eating the magical grass that is planted
on Farmer John's field.
Farmer John wants to know the maximum attractiveness index of a picture he can
take after each of the \(Q\) updates.
Problem credits: Brian Law and Cici Liu
SCORING
- Inputs 3-6: \(N \leq 50, Q \leq 100\)
- Inputs 7-10: \(N \leq 50\)
- Inputs 11-18: No additional constraints.
Problem credits: Brian Law and Cici Liu
The first line contains integers \(N\) and \(K\).
The following line contains an integer \(Q\).
Each of the following \(Q\) lines contains three integers: \(r\), \(c\), and \(v\),
which are the row, column, and new beauty value, respectively
(\(1 \leq r, c \leq N, 1 \leq v \leq 10^6\)). It is guaranteed that the new beauty
value is greater than the beauty value at that location before.
Output \(Q\) lines, corresponding to the maximum attractiveness index of a picture
after each update.
4 2
3
2 2 11
3 4 3
3 1 10011
11
111After the first update, a picture with the maximum attractiveness index is the
picture with upper left corner \((2, 2)\) and lower right corner \((3, 3)\), which
has an attractiveness index of \(11 + 0 + 0 + 0 = 11\).
The second update does not affect the maximum attractiveness index.
After the third update, the picture with the maximum attractiveness index
changes to the picture with upper left corner \((2, 1)\) and lower right corner
\((3, 2)\), which has an attractiveness index of \(0 + 11 + 100 + 0 = 111\).
3 1
3
2 2 3
2 2 5
2 2 73
5
7There is only one cow with a positive beauty value, so the maximum
attractiveness index will always include that cow.
riseoj 작성
출처 올림피아드 > USACO > 2025-2026 > First Contest > Bronze
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