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LABYR1 - Labyrinth

The northern part of the Pyramid contains a very large and complicated labyrinth. The labyrinth is divided into square blocks, each of them either filled by rock, or free. There is also a little hook on the floor in the center of every free block. The ACM have found that two of the hooks must be connected by a rope that runs through the hooks in every block on the path between the connected ones. When the rope is fastened, a secret door opens. The problem is that we do not know which hooks to connect. That means also that the neccessary length of the rope is unknown. Your task is to determine the maximum length of the rope we could need for a given labyrinth.


The input consists of T test cases. The number of them (T) is given on the first line of the input file. Each test case begins with a line containing two integers C and R (3 <= C,R <= 1000) indicating the number of columns and rows. Then exactly R lines follow, each containing C characters. These characters specify the labyrinth. Each of them is either a hash mark (#) or a period (.). Hash marks represent rocks, periods are free blocks. It is possible to walk between neighbouring blocks only, where neighbouring blocks are blocks sharing a common side. We cannot walk diagonally and we cannot step out of the labyrinth.

The labyrinth is designed in such a way that there is exactly one path between any two free blocks. Consequently, if we find the proper hooks to connect, it is easy to find the right path connecting them.


Your program must print exactly one line of output for each test case. The line must contain the sentence "Maximum rope length is X." where Xis the length of the longest path between any two free blocks, measured in blocks.


Sample Input:

3 3
7 6

Sample output:

Maximum rope length is 0.
Maximum rope length is 8.
Warning: large Input/Output data, be careful with certain languages

hide comments
Daksh: 2015-08-23 22:53:13

first, try to solve PT07Z . nice prob.

Liquid_Science: 2015-07-26 16:14:33

my first ac in one go , finally
Though solution is the slowest in java (2 sec)
mixed emotions -_-

Last edit: 2015-07-26 16:15:31
rp007: 2015-07-24 09:27:41

Awesome Question (BFS+BFS) "Maja aa gaya Tel Laga Ke" .... :-)

goyal: 2015-07-11 16:24:40

maja aa gaya tel laga k:)
i think first try pt07z and then this

tarunsai: 2015-07-06 09:21:23

very easy BFS+BFS :)

SangKuan: 2015-07-01 05:30:55

17 wa,now got ac...o(∩∩)o...use dfs or bfs,not esay

sujit yadav: 2015-06-21 00:55:37

i hate c++14 compiler gives me 4 compilation error .. wtf y? :(

peeyush taneja: 2015-06-16 16:40:57

After 3 wa finally AC

Dipti Singhal: 2015-06-12 11:58:42

Giving Runtime Error!

Rishabh: 2015-06-08 11:50:46

"there is exactly one path between any two free blocks". Does this means that there will be only one connected component (island) ?

Added by:adrian
Time limit:5s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel Pentium G860 3GHz)
Resource:ACM Central European Programming Contest, Prague 1999