400 - Unix ls

The computer company you work for isintroducing a brand new computer line and is developing a new Unix-likeoperating system to be introduced along with the new computer. Your assignmentis to write the formatter for the ls function.

Your program will eventually read input froma pipe (although for now your program will read from the input file). Input toyour 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 willbe between 1 and 60 (inclusive) characters in length and will be formatted intoleft-justified columns. The rightmost column will be the width of the longestfilename and all other columns will be the width of the longest filename plus2. There will be as many columns as will fit in 60 characters. Your programshould use as few rows (R) as possible with rows being filled tocapacity from left to right.

Input

The input file will contain an indefinitenumber of lists of filenames. Each list will begin with a line containing asingle integer (  ).There will then be N lines each containing one left-justifiedfilename and the entire line's contents (between 1 and 60 characters) areconsidered to be part of the filename. Allowable characters are alphanumeric (ato z, A to Z, and 0 to 9) and from thefollowing set { ._- } (not including the curly braces). There will beno illegal characters in any of the filenames and no line will be completelyempty.

Immediately following the last filename willbe the N for the next set or the end of file. You should readand format all sets in the input file.

Output

For each set of filenames you should print aline 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

tiny

2short4me

very_long_file_name

shorter

size-1

size2

size3

much_longer_name

12345678.123

mid_size_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        size3               

much_longer_name     tiny                

shorter              very_long_file_name 

------------------------------------------------------------

Alfalfa        Cotton         Joe            Porky         

Buckwheat      Darla          Mrs_Crabapple  Stimey        

Butch          Froggy         P.D.           Weaser         

------------------------------------------------------------

Alice      Chris       Jan         Marsha      Ruben      

Bobby      Cindy       Jody        Mike        Shirley    

Buffy      Danny       Keith       Mr._French  Sissy      

Carol      Greg        Lori        Peter

代码:

#include<iostream>

#include<string>

#include<algorithm>

#include<iomanip>

using namespacestd;

int  main()

{

    cout.setf(ios::left);

    int sum;

    while(cin>>sum)

    {

        string s[110];

        int m=0;

        for(int i=0;i<sum;i++)

        {

            cin>>s[i+1];

            if(s[i+1].size()>m)

            {

                m=s[i+1].size();

            }

        }

        int c=(60-m)/(m+2)+1;

        int r=(sum-1)/c+1;

        sort(s+1,s+sum+1);

        cout<<"------------------------------------------------------------\n";

        for(int i=1;i<=r;i++)

        {

            for(int j=1;j<c;j++)

            {

                if((i+(j-1)*r)<=sum)

                {

                   cout<<setw(m+2)<<s[i+(j-1)*r];

                }

            }

            if((i+(c-1)*r)<=sum)

            {

               cout<<setw(m)<<s[i+(c-1)*r];

            }

            cout<<endl;

        }

    }

}

题意:

题目：对输入的每组文件名进行规则化输出，除了最后一列，其他列的宽度为maxlen+2，最后一列宽度为maxlen。maxlen为最长字符串的长度。

对字符串排序，然后计算相应长度，得出maxlen。现在需要确定列数和行数。列数：设有n+1列。则(maxlen+2)*n+maxlen<=60，则n<=(60-maxlen)/(maxlen+2)，n是整数，且n需要最大化，则n即为右边值。行数：对( q 除以 lie )取上整，这里的q是总共字符串数。这里是从左往右排，一列排满了再排下一列。注意整数相除+1,-1的调试