gt5163b@prism.gatech.edu (Brian McNamara!) once said:
>Write a program which will accept a haiku as input and create a
>line-index based off each word in the haiku.  For example, given the
>input:
>
>   c++ is the
>   favorite extant language
>   of the brian mac
>
>the output should be
>
>            of the brian mac
>                   c++ is the
>          favorite extant language
>                   favorite extant language
>               c++ is the
>   favorite extant language
>      of the brian mac
>                   of the brian mac
>            c++ is the
>                of the brian mac

Here's my solution (commentary to follow):

#include <set>
#include <string>
#include <algorithm>
#include <functional>

typedef pair<string,typename string::size_type> Index;

struct Cmp : public binary_function<Index,Index,bool> {
   bool operator()( const Index& x, const Index& y ) const {
      return lexicographical_compare(x.first.begin()+x.second,x.first.end(),
                                     y.first.begin()+y.second,y.first.end());
   }
};

typedef set<Index,Cmp> Set;

unsigned int N = 0;

void insert( Set& s, const string& x ) {
   string::const_iterator i = x.begin();
   for(;;) {
      i = find_if( i, x.end(), bind1st(not_equal_to<char>(),' ') );
      if( i == x.end() ) 
         break;
      unsigned int len = i - x.begin();
      N = max( len, N );
      s.insert( make_pair(x,len) );
      i = find_if( i, x.end(), bind1st(equal_to<char>(),' ') );
   }
}

void print( const Index& x, unsigned int n ) {
   for( unsigned int i=0; i<n-x.second; i++ )
      cout << " ";
   cout << x.first << endl;
}

int main() {
   Set s;
   string x;

   while( cin ) {
      getline( cin, x );
      insert( s, x );
   }
   for( Set::iterator i=s.begin(); i!=s.end(); i++ )
      print( *i, N );

   return 0;
}