UVA 400 Unix ls

 

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
 #define LEN 60+10
 char fn[100][LEN];//to make sure the range is safe
 int cmp(const void* a,const void *b);

 int main()
{
    int n,width=0;
    int columns,rows;
    #ifndef ONLINE_JUDGE
        freopen("in.txt","r",stdin);
        //freopen("ou.txt","w",stdout);
     #endif
    while(scanf("%d",&n)==1)
    {
        width=0;
        for(int i=0; i<n; i++)//input the filenames of n
         {
            scanf("%s",fn[i]);int len=strlen(fn[i]);
            if(width<len)//get the longest filename
                 width=len;
        }
        width+=2;//the Requestment
        int R=60>width?60:width;//
        columns=R/width;
        rows=(n+columns-1)/columns;//get the row and it don not need the judgement
        //qsort
        qsort(fn,(int)n,sizeof(char)*(LEN),cmp);
        //put them in the right pos.
        printf("------------------------------------------------------------\n");
        for(int i=0;i<rows;i++)
        {
            for(int j=i,k=0;k<columns && j<n;j=j+rows,k++)
            {
                printf("%s",fn[j]);
                int len = width-strlen(fn[j]);
                for( int l=0;l<len;l++) putchar(' ');
            }
            printf("\n");
        }
    }
    return 0;
}
int cmp(const void *a,const  void *b){
    return strcmp((char *)a,(char *)b);
}