1995 ACM South Central Region 
Programming Contest 
 
Problem #1: Unix ls 
 
Source File: ls.pas 
             ls.cpp 
             ls.bas 
           ls.c 
Input File: ls.in 
Output File: ls.out 
 
The computer company you work for is introducing a brand new computer 
line and is developing a new Unix-like operating system to be 
introduced along with the new computer.  Your assignment is to write 
the formatter for the ls function. 
 
Your program will eventually read input from a pipe (although for now 
your program will read from the input file).  Input to your program 
will consist of a list of (F) filenames that you will sort (ascending 
based on the ASCII character values) and format into (C) columns based 
on the length (L) of the longest filename.  Filenames will be between 1 
and 60 (inclusive) characters in length and will be formatted into 
left-justified columns.  The rightmost column will be the width of the 
longest filename and all other columns will be the width of the longest 
filename plus 2.  There will be as many columns as will fit in 60 
characters.  Your program should use as few rows (R) as possible with 
rows being filled to capacity from left to right. 
 
Input 
The input file will contain an indefinite number of lists of filenames.  
Each list will begin with a line containing a single integer (1<= N <= 
100).  There will then be N lines each containing one left-justified 
filename and the entire line's contents (between 1 and 60 characters) 
are considered to be part of the filename.  Allowable characters are 
alphanumeric (a to z, A to Z, and 0 to 9) and from the following set { 
._- } (not including the curly braces).  There will be no illegal 
characters in any of the filenames and no line will be completely 
empty. 
 
Immediately following the last filename will be the N for the next set 
or the end of file.  You should read and format all sets in the input 
file. 
 
Output 
For each set of filenames you should print a line of exactly 60 dashes 
(-) followed by the formatted columns of filenames.  The sorted 
filenames 1 to R will be listed down column 1; filenames R+1 to 2R 
listed down column 2; etc. 
 
Sample Input 
10 
long-file-name 
the longest file name 
short 
tiny 
abc 
mid-length 
88888888.333 
longer_filename 
2short4me 
another long name 
12 
Weaser 
Alfalfa 
Stimey 
Buckwheat 
Porky 
Joe 
Darla 
Cotton 
Butch 
Froggy 
Mrs_Crabapple 
P.D. 
19 
Mr._French 
Jody 
Buffy 
Sissy 
Keith 
Danny 
Lori 
Chris 
Shirley 
Marsha 
Jan 
Cindy 
Carol 
Mike 
Greg 
Peter 
Bobby 
Alice 
Ruben 
 
Sample Output 
------------------------------------------------------------ 
12345678.123         size-1                
2short4me            size2                 
mid_size_name        tiny                  
much_longer_name     very_long_file_name   
shorter              size3                 
------------------------------------------------------------ 
Alfalfa        Cotton         Joe            Stimey          
Buckwheat      Darla          Mrs_Crabapple  Weaser          
Butch          Froggy         Porky          P.D.            
------------------------------------------------------------ 
Alice       Chris       Jan         Marsha      Shirley      
Bobby       Cindy       Jody        Mike        Sissy        
Buffy       Danny       Keith       Mr._French  Ruben        
Carol       Greg        Lori        Peter