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.
Input
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.
Output
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.
Example
Sample Input: 2 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
xamitksx:
20160402 14:49:57
BFS + BFS or DFS + DFS both are fine ..... reading input as R C instead of C R costed me 3 WA Last edit: 20160402 14:50:24 

try2catch:
20160305 06:31:04
my 80th..... 1st go AC _


Archit Gupta:
20160224 21:22:25
Be careful about the full stop at the end 2 WA coz of that


Saksham :
20160220 01:43:49
my 200th 

lakshay_v06:
20160119 15:24:57
The given graph will be a fully connected graph. ( as the question says) 

Daksh:
20150823 22:53:13
first, try to solve PT07Z . nice prob. 

Liquid_Science:
20150726 16:14:33
my first ac in one go , finally


rp007:
20150724 09:27:41
Awesome Question (BFS+BFS) "Maja aa gaya Tel Laga Ke" .... :) 

goyal:
20150711 16:24:40
maja aa gaya tel laga k:)


tarunsai:
20150706 09:21:23
very easy BFS+BFS :) 
Added by:  adrian 
Date:  20040606 
Time limit:  5s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All 
Resource:  ACM Central European Programming Contest, Prague 1999 