Codeforces Round 191 (Div. 2)
D
Block Tower
Codeforces
1900
原题
← CE →
翻译中…

After too much playing on paper, Iahub has switched to computer games. The game he plays is called "Block Towers". It is played in a rectangular grid with $*n*$ rows and $*m*$ columns (it contains $*n* × *m*$ cells). The goal of the game is to build your own city. Some cells in the grid are big holes, where Iahub can't build any building. The rest of cells are empty. In some empty cell Iahub can build exactly one tower of two following types:

翻译中…
  1. Blue towers. Each has population limit equal to $100$.
  2. Red towers. Each has population limit equal to $200$. However, it can be built in some cell only if in that moment at least one of the neighbouring cells has a Blue Tower. Two cells are neighbours is they share a side.
翻译中…

Iahub is also allowed to destroy a building from any cell. He can do this operation as much as he wants. After destroying a building, the other buildings are not influenced, and the destroyed cell becomes empty (so Iahub can build a tower in this cell if needed, see the second example for such a case).

翻译中…

Iahub can convince as many population as he wants to come into his city. So he needs to configure his city to allow maximum population possible. Therefore he should find a sequence of operations that builds the city in an optimal way, so that total population limit is as large as possible.

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He says he's the best at this game, but he doesn't have the optimal solution. Write a program that calculates the optimal one, to show him that he's not as good as he thinks.

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Input

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The first line of the input contains two integers $*n*$ and $*m*$ ($1 ≤ *n*, *m* ≤ 500$). Each of the next $*n*$ lines contains $*m*$ characters, describing the grid. The $*j*$-th character in the $*i*$-th line is '.' if you're allowed to build at the cell with coordinates $(*i*, *j*)$ a tower (empty cell) or '#' if there is a big hole there.

翻译中…

Output

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Print an integer $*k*$ in the first line $(0 ≤ *k* ≤ 10^{6})$ — the number of operations Iahub should perform to obtain optimal result.

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Each of the following $*k*$ lines must contain a single operation in the following format:

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  1. «B x y» $(1 ≤ *x* ≤ *n*, 1 ≤ *y* ≤ *m*)$ — building a blue tower at the cell $(*x*, *y*)$;
  2. «R x y» $(1 ≤ *x* ≤ *n*, 1 ≤ *y* ≤ *m*)$ — building a red tower at the cell $(*x*, *y*)$;
  3. «D x y» $(1 ≤ *x* ≤ *n*, 1 ≤ *y* ≤ *m*)$ — destroying a tower at the cell $(*x*, *y*)$.
翻译中…

If there are multiple solutions you can output any of them. Note, that you shouldn't minimize the number of operations.

翻译中…

样例

Input #1
2 3
..#
.#.
Output #1
4
B 1 1
R 1 2
R 2 1
B 2 3
InputCopy OutputCopy
Input #2
1 3
...
Output #2
5
B 1 1
B 1 2
R 1 3
D 1 2
R 1 2
InputCopy OutputCopy
题目信息
题号
327D
时间限制
2 s
内存限制
256 MB
标签
构造
DFS 及类似
图论

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。