ACM International Collegiate
Programming Contest, Asia-Amritapuri Site, 2011
Problem G: Here Be Dragons!
The Triwizard Tournament's third task is to negotiate a corridor of
many segments, and reach the other end. The corridor is N segments
long. The ith segment is either empty or has a dragon. Harry cannot
pass the dragon and will have no option but to retreat if he encounters
one. Is it possible for him to reach the exit starting from the
entrance?
Input (STDIN):
The first line contains the number of test cases T.
Each of the next T lines contains a string describing the corridor. The
ith character is either a '.' if the segment is empty, or a 'D' if the
segment contains a dragon.
Output (STDOUT):
Output T lines, each containing either the string "Possible" if you can
reach the exit, and "You shall not pass!" if it is not possible to
reach the exit.
Constraints:
1 <= T <= 50
1 <= N <= 50
Time Limit: 1 s
Memory Limit: 32 MB
Sample Input:
3
..
..D.
D..D
Sample Output:
Possible
You shall not
pass!
You shall not
pass!