MAKEMAZE  VALIDATE THE MAZE
MAZE MAKING
There are many algorithms to generate maze. (http://en.wikipedia.org/wiki/Maze_generation_algorithm). After generating the maze we’ve to validate whether it’s a valid maze or not. A valid maze has exactly one entry point and exactly one exit point (exactly 2 openings in the edges) and there must be atleast one path from the entry point to exit point.
Given a maze, just find whether the maze is "valid" or "invalid".
Input Specification:
The first line consists of an integer t, the number of test cases. Then for each test case, the first line consists of two integers m and n, the number of rows and columns in the maze. Then contains the description of the matrix M of order mxn. M[i][j]=# represents a wall and M[i][j]='.' represents a space.
Output Specification:
For each test case find whether the maze is "valid" or "invalid".
Input Constraints:
1<=t<=10000
1<=m<=20
1<=n<=20
Sample Input:
6 4 4 #### #... #.## #.## 5 5 #.### #..## ##..# #.#.# ###.# 1 1 . 5 1 # # . . # 2 2 #. .# 3 4 #..# #.## #.##
Sample Output:
valid valid invalid valid invalid invalid
hide comments
RAMSDEN:
20140627 09:27:46
many WAs due to silly mistake


Master_Mind:
20140614 09:02:12
plzz provide some tricky cases.


Vipul Pandey:
20140204 21:53:35
take input character by character using cin or getchar as there are spaces in the input. costed me WA. Last edit: 20140204 21:54:02 

Rishav Goyal:
20140203 12:35:30
Awesome fun at WA ;) 

P_Quantum:
20140119 07:04:47
easy one..!! 

The Joker:
20131212 23:21:48
can someone give some tricky test cases plz...


BLANKRK:
20131212 23:21:48
enjoyed solving this.... :) 

sobhan:
20131212 23:21:48
plz give me input :) 

shiva_hellgeek:
20131212 23:21:48
the problem is really nice.


mudiyala:
20131212 23:21:48
Loved solving it ~~!!! :D Wonderful testcases :) 
Added by:  cegprakash 
Date:  20120511 
Time limit:  1s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 GOSU 