Sphere Online Judge

SPOJ Problem Set (classical)

38. Labyrinth

Problem code: LABYR1


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
Added by:Adrian Kosowski
Date:2004-06-06
Time limit:5s
Source limit:50000B
Memory limit:256MB
Cluster: Pyramid (Intel Pentium III 733 MHz)
Languages:All
Resource:ACM Central European Programming Contest, Prague 1999

hide comments
2014-08-16 03:25:03 anand pandey
why this code not working????
2014-08-16 03:24:39 anand pandey
[code removed by cyclops; see notes below, "1. Don't post any source code here."]

Last edit: 2014-08-16 03:56:04
2014-08-08 15:34:53 Mitch Schwartz
@arbit: Read the problem statement carefully.
2014-08-08 11:24:10 arbit
Can I assume that there will not be any inputs like this?

#####
#...#
#...#
#...#
#####

I mean where there are more than one paths from a dot to another. Should we expect inputs like this too?
2014-07-07 18:34:17 stl*_easy&&_*goody
can't undrstnd d ques itslf :(
2014-07-04 05:24:18 sobriquet
Longest code ever written. 12 KB. Forgot the correct O/P format.
2014-07-02 21:32:15 Archit Jain
nice learned something new..
2014-06-13 15:24:32 Petar Bosnjak
be careful about length and lenght costed me 1 WA
2014-06-13 13:18:42 Raj Mehta
giving seg fault don't knw where
plz...help
http://ideone.com/C8Q9HX
tried all tc in comments getting correct answers
2014-03-14 02:24:39 Jean-Ralph Aviles
try
1
5 5
##.##
##.##
.....
##.##
##.##

answer is 4
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