ABCPATH  ABC Path
You will be given a 2dimensional grid of letters. Find the length of the longest path of consecutive letters, starting at 'A'. Paths can step from one letter in the grid to any adjacent letter (horizontally, vertically, or diagonally).
For example, in the following grid, there are several paths from 'A' to 'D', but none from 'A' to 'E':
One such path is:
Input
Each test case will start with a line contains two integers H, W the height and width of the grid respectively 1 <= H, W <= 50. Then H lines follow each of W uppercase letters only. Input terminates with H = 0 and W = 0.
Output
For each test case print “Case C: X” without quotes where C is the case number starting with 1 and X is the solution.
Example
Sample Input: 4 3 ABE CFG BDH ABC 0 0 Sample Output: Case 1: 4
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c0der_ace:
20180705 15:23:11
Simple DFS !! Just make once used characters unusable for further times as they can never help to reach farther than they did last time ;) 

selva1996:
20180525 16:51:05
Good one Last edit: 20180526 06:23:18 

frozen7:
20180204 07:39:51
use multisource bfs 

prasanth292130:
20180117 18:00:13
AC in 1 go. :)


chetan4060:
20171223 08:44:59
nice practice question:) 

mohaimin66:
20170828 07:57:04
Try this.


saurav52:
20170813 09:27:12
used recursion :)


saurav114:
20170730 19:56:06
Can not figure out an iterative solution though.. 

lucifer_398:
20170722 19:22:59
simple DFS...dont forget the case when no 'A' is present!!


tusharuppal:
20170618 11:22:10
just dfs with memo..otherwise tle. ;) 
Added by:  Ali Arous 
Date:  20111105 
Time limit:  0.458s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 
Resource:  FCIS Local Contest 2012 