--- /dev/null
+// -*- C++ -*-
+
+// Copyright (C) 2005, 2006, 2007, 2009 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the terms
+// of the GNU General Public License as published by the Free Software
+// Foundation; either version 3, or (at your option) any later
+// version.
+
+// This library is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+// General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+
+// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
+
+// Permission to use, copy, modify, sell, and distribute this software
+// is hereby granted without fee, provided that the above copyright
+// notice appears in all copies, and that both that copyright notice
+// and this permission notice appear in supporting documentation. None
+// of the above authors, nor IBM Haifa Research Laboratories, make any
+// representation about the suitability of this software for any
+// purpose. It is provided "as is" without express or implied
+// warranty.
+
+/**
+ * @file trie_dna_example.cpp
+ * An example showing how to use a trie for storing DNA strings.
+ */
+
+/**
+ * This example shows how to use a PATRICIA trie for storing
+ DNA strings. The main point is writing element-access traits
+ for these strings.
+*/
+
+#include <cassert>
+#include <iostream>
+#include <cstdlib>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/trie_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+// DNA is represented by a string.
+typedef string dna_t;
+
+// Following is an element access traits for a DNA string.
+struct dna_string_e_access_traits
+{
+public:
+ typedef size_t size_type;
+ typedef dna_t key_type;
+ typedef const key_type& const_key_reference;
+ typedef char e_type;
+ typedef string::const_iterator const_iterator;
+
+ enum
+ {
+ // Number of distinct elements. This is 4 = |{'A', 'C', 'G', 'T'}|
+ max_size = 4
+ };
+
+ // Returns a const_iterator to the firstelement of r_key.
+ inline static const_iterator
+ begin(const_key_reference r_key)
+ { return r_key.begin(); }
+
+ // Returns a const_iterator to the after-lastelement of r_key.
+ inline static const_iterator
+ end(const_key_reference r_key)
+ { return r_key.end(); }
+
+ // Maps an element to a position.
+ inline static size_t
+ e_pos(e_type e)
+ {
+ switch(e)
+ {
+ case 'A':
+ return 0;
+ case 'C':
+ return 1;
+ case 'G':
+ return 2;
+ case 'T':
+ return 3;
+ default:
+ std::abort();
+ };
+ }
+};
+
+// A PATRICIA trie with DNA string element-access traits.
+typedef dna_string_e_access_traits traits_type;
+typedef trie<dna_t, string, traits_type> trie_type;
+
+int main()
+{
+ trie_type t;
+
+ // Now map some DNAs to diseases in namespace STD.
+ t["ACCGGTTACTGGTA"] = "gonorrhea";
+ t["CCGTTATCGGTA"] = "syphlis";
+
+ // Check gonorrhea already contracted.
+ assert(t.find("ACCGGTTACTGGTA") != t.end());
+
+ return 0;
+}
+