Last year (2009), the Google Code Jam featured an interesting problem as the first problem in Round 1B: Decision Tree
As the problem seemed tailored for Lisp-like languages, we spontaneously had an exciting codegolf here on SO, in which a few languages managed to solve the problem in fewer characters than any Lisp variety, using quite a number of different techniques.
This year's Round 1B Problem A (File Fix-it) also seems tailored for a particular family of languages, Unix shell scripts. So continuing the "1B-A tradition" would be appropriate. :p But which language will end up with the shortest code? Let us codegolf and see!
Problem description (adapted from official page):
You are given T test cases. Each test case contains N lines that list the full path of all directories currently existing on your computer. For example:
/home
/home/awesome
/home/awesome/wheeeeeee
/home/awesome/wheeeeeee/codegolfrocks
/home/thecakeisalie
Next, you are given M lines that list the full path of directories you would like to create. They are in the same format as the previous examples. You can create a directory using the mkdir command, but you can only do so if the parent directory already exists. For example, to create the directories /pyonpyon/fumufumu/yeahyeah and /pyonpyon/fumufumu/yeahyeahyeah, you would need to use mkdir four times:
mkdir /pyonpyon
mkdir /pyonpyon/fumufumu
mkdir /pyonpyon/fumufumu/yeahyeah
mkdir /pyonpyon/fumufumu/yeahyeahyeah
For each test case, return the number of times you have to call mkdir to create all the directories you would like to create.
Input
Input consists of a text file whose first line contains the integer T, the number of test cases. The rest of the file contains the test cases.
Each test case begins with a line containing the integers N and M, separated by a space.
The next N lines contain the path of each directory currently existing on your computer (not including the root directory /). This is a concatenation of one or more non-empty lowercase alphanumeric strings, each preceded by a single /.
The following M lines contain the path of each directory you would like to create.
Output
For each case, print one line containing Case #X: Y, where X is the case number and Y is the solution.
Limits
1 ≤ T ≤ 100.
0 ≤ N ≤ 100.
1 ≤ M ≤ 100.
Each path contains at most 100 characters.
Every path appears only once in the list of directories already on your computer, or in the list of desired directories. However, a path may appear on both lists, as in example case #3 below.
If a directory is in the list of directories already on your computer, its parent directory will also be listed, with the exception of the root directory /.
The input file is at most 100,000 bytes long.
Example
Larger sample test cases may be downloaded here.
Input:
3
0 2
/home/sparkle/pyon
/home/sparkle/cakes
1 3
/z
/z/y
/z/x
/y/y
2 1
/moo
/moo/wheeeee
/moo
Output:
Case #1: 4
Case #2: 4
Case #3: 0
Code Golf
Please post your shortest code in any language that solves this problem. Input and output may be handled via stdin and stdout or by other files of your choice. Please include a disclaimer if your code has the potential to modify or delete existing files when executed.
Winner will be the shortest solution (by byte count) in a language with an implementation existing prior to the start of Round 1B 2010. So while you are free to use a language you've just made up in order to submit a 0-byte solution, it won't count, and you'll probably get downvotes. ^_^
Standings
Now on a single line!
This solution is 63 characters, but will not run in a reasonable amount of time for test cases with thousands of paths (over 8 minutes), so I have opted to not count it.
n%(~,{'Case #'\)@': '\(~1$+@[]@{\('/':!%@\{[n!++:!]|}/}*,@-n@}/
The faster 65 character solution:
n%(~,{'Case #'\)@': '\(~1$+@[]@{\('/':!%@\{[n!++:!]+}/.&}*,@-n@}/
Kudos to marcog for the algorithm!