UVa 644 Immediate Decodability

UVa 644 Immediate Decodability

题目没有给出具体的规模，因此没有用枚举。我的做法是维护一棵Trie，把01串按长度从大到小的次序插入，这样就可以在插入时判断是否为之前某个长度更大串的前缀。尽管如此，依然用了0.408s的时间，可能与用cin/cout输入输出有关。
以下是我的代码：

#include < iostream >
#include < vector >
#include < string >
#include < algorithm >
#include < cstdio >
using   namespace  std;
const   int  kMaxn( 10007 );

bool  cmp( const   string   & sa, const   string   & sb)
{
     return  (sa.size() > sb.size()  ||  (sa.size() == sb.size()  &&  sa < sb));
}

struct  TreeNode
{
    TreeNode():left_(NULL),right_(NULL) {}

    TreeNode  * left_, * right_;
};
class  Trie
{
     public :
        Trie()
        {
            father_ = new  TreeNode;
        }
         bool  Insert( const   string   & s)
        {
             bool  re( false );
            TreeNode  * p(father_);
             for ( int  i = 0 ;i < s.size();i ++ )
            {
                 if (s[i] == ' 0 '   &&   ! p -> left_)
                {
                    p -> left_ = new  TreeNode;
                     if (i == s.size() - 1 )
                        re = true ;
                }
                 else   if (s[i] == ' 1 '   &&   ! p -> right_)
                {
                    p -> right_ = new  TreeNode;
                     if (i == s.size() - 1 )
                        re = true ;
                }
                 if (s[i] == ' 0 ' )
                    p = p -> left_;
                 else
                    p = p -> right_;
            }
             return  re;
        }

     private :
        TreeNode  * father_;
};

int  main()
{
     /*
    freopen("data.in","r",stdin);
    freopen("data.out","w",stdout);
    // */

     int  T( 0 );
     string  t;
     while (cin >> t)
    {
        vector < string >  r;
         while (t != " 9 " )
        {
            r.push_back(t);
            cin >> t;
        }

        sort(r.begin(),r.end(),cmp);
        Trie trie;
         bool  success( true );
         for (vector < string > ::iterator i = r.begin();i != r.end();i ++ )
             if ( ! trie.Insert( * i))
            {
                success = false ;
                 break ;
            }

        T ++ ;
         if (success)
            cout << " Set  " << T << "  is immediately decodable " << endl;
         else  cout << " Set  " << T << "  is not immediately decodable " << endl;
    }

     return   0 ;
}