Lena and Matrix

2000ms

262144K

Description:

Lena is a beautiful girl who likes logical puzzles.

As a gift for her birthday, Lena got a matrix puzzle!

The matrix consists of $$$n$$$ rows and $$$m$$$ columns, and each cell is either black or white. The coordinates $$$(i,j)$$$ denote the cell which belongs to the $$$i$$$-th row and $$$j$$$-th column for every $$$1\leq i \leq n$$$ and $$$1\leq j \leq m$$$. To solve the puzzle, Lena has to choose a cell that minimizes the Manhattan distance to the farthest black cell from the chosen cell.

More formally, let there be $$$k \ge 1$$$ black cells in the matrix with coordinates $$$(x_i,y_i)$$$ for every $$$1\leq i \leq k$$$. Lena should choose a cell $$$(a,b)$$$ that minimizes $$$$$$\max_{i=1}^{k}(|a-x_i|+|b-y_i|).$$$$$$

As Lena has no skill, she asked you for help. Will you tell her the optimal cell to choose?

Input:

There are several test cases in the input data. The first line contains a single integer $$$t$$$ ($$$1\leq t\leq 10\,000$$$) — the number of test cases. This is followed by the test cases description.

The first line of each test case contains two integers $$$n$$$ and $$$m$$$ ($$$2\leq n,m \leq 1000$$$) — the dimensions of the matrix.

The following $$$n$$$ lines contain $$$m$$$ characters each, each character is either 'W' or 'B'. The $$$j$$$-th character in the $$$i$$$-th of these lines is 'W' if the cell $$$(i,j)$$$ is white, and 'B' if the cell $$$(i,j)$$$ is black.

It is guaranteed that at least one black cell exists.

It is guaranteed that the sum of $$$n\cdot m$$$ does not exceed $$$10^6$$$.

Output:

For each test case, output the optimal cell $$$(a,b)$$$ to choose. If multiple answers exist, output any.

Sample Input:

5
3 2
BW
WW
WB
3 3
WWB
WBW
BWW
2 3
BBB
BBB
5 5
BWBWB
WBWBW
BWBWB
WBWBW
BWBWB
9 9
WWWWWWWWW
WWWWWWWWW
BWWWWWWWW
WWWWWWWWW
WWWWBWWWW
WWWWWWWWW
WWWWWWWWW
WWWWWWWWW
WWWWWWWWB

Sample Output:

Note:

In the first test case the two black cells have coordinates $$$(1,1)$$$ and $$$(3,2)$$$. The four optimal cells are $$$(1,2)$$$, $$$(2,1)$$$, $$$(2,2)$$$ and $$$(3,1)$$$. It can be shown that no other cell minimizes the maximum Manhattan distance to every black cell.

In the second test case it is optimal to choose the black cell $$$(2,2)$$$ with maximum Manhattan distance being $$$2$$$.

Informação

Provedor Codeforces

Código CF1689D