[3] | 1 | /* -*- mode: C++; indent-tabs-mode: nil; -*- |
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| 2 | * |
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| 3 | * This file is a part of LEMON, a generic C++ optimization library. |
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| 4 | * |
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| 5 | * Copyright (C) 2003-2008 |
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| 6 | * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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| 7 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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| 8 | * |
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| 9 | * Permission to use, modify and distribute this software is granted |
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| 10 | * provided that this copyright notice appears in all copies. For |
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| 11 | * precise terms see the accompanying LICENSE file. |
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| 12 | * |
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| 13 | * This software is provided "AS IS" with no warranty of any kind, |
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| 14 | * express or implied, and with no claim as to its suitability for any |
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| 15 | * purpose. |
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| 16 | * |
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| 17 | */ |
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| 18 | |
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[11] | 19 | namespace lemon { |
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[3] | 20 | /** |
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[10] | 21 | [PAGE]hello_lemon[PAGE] Compile Your First Code |
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[6] | 22 | |
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[11] | 23 | First of all you have to install LEMON on your system (see |
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| 24 | \ref install for instructions). |
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| 25 | After that you can paste the following code segment into a file |
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| 26 | <tt>hello_lemon.cc</tt> to have a first working program that uses LEMON. |
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[6] | 27 | |
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| 28 | \dontinclude hello_lemon.cc |
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| 29 | \skip #include |
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| 30 | \until } |
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| 31 | |
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| 32 | First let us briefly explain how this example program works. |
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[9] | 33 | (The used notions will be discussed in detail in the following sections.) |
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[6] | 34 | |
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| 35 | After some convenience typedefs we create a directed graph (\e digraph) |
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| 36 | and add some nodes and arcs to it. |
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| 37 | ListDigraph is one of the digraph classes implemented in LEMON. |
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| 38 | It is based on linked lists, therefore iterating through its nodes and |
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| 39 | arcs is fast. |
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| 40 | |
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| 41 | Then we iterate through all nodes of the digraph and print their unique |
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| 42 | IDs. We use a constructor of the node iterator to initialize it to the |
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| 43 | first node. |
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| 44 | The <tt>operator++</tt> is used to step to the next node. After the last |
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| 45 | node the iterator becomes invalid (i.e. it is set to \c INVALID). |
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| 46 | This is what we exploit in the stop condition. |
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| 47 | We iterate through all arcs of the digraph very similarly and print the |
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| 48 | IDs of their source (tail) and target (head) nodes using the \c source() |
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| 49 | and \c target() member functions. |
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| 50 | |
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| 51 | After that we create an arc map, which is actually a mapping that assigns |
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| 52 | an \c int value (length) to each arc, and we set this value for each arc. |
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| 53 | Finally we iterate through all arcs again and print their lengths. |
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| 54 | |
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[9] | 55 | Now let us compile this simple example program. |
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[6] | 56 | |
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[10] | 57 | [SEC]hello_lemon_system[SEC] If LEMON is Installed System-Wide |
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[6] | 58 | |
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[9] | 59 | If LEMON is installed system-wide (into directory \c /usr/local), |
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| 60 | then it is very easy to compile this program with the |
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[6] | 61 | following command (the argument <tt>-lemon</tt> tells the compiler |
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| 62 | that we are using the installed LEMON): |
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| 63 | |
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| 64 | \verbatim |
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[9] | 65 | g++ -lemon hello_lemon.cc -o hello_lemon |
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[6] | 66 | \endverbatim |
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| 67 | |
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| 68 | As a result you will get the exacutable \c hello_lemon in the current |
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| 69 | directory, which you can run by the following command. |
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| 70 | |
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| 71 | \verbatim |
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| 72 | ./hello_lemon |
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| 73 | \endverbatim |
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| 74 | |
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[10] | 75 | [SEC]hello_lemon_user[SEC] If LEMON is Installed User-Local |
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[6] | 76 | |
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| 77 | Compiling the code is a bit more difficult if you installed LEMON |
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| 78 | user-local into a directory (e.g. <tt>~/lemon</tt>) or if you just |
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| 79 | skipped the step <tt>make install</tt>. |
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| 80 | You have to issue a command like this. |
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| 81 | |
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| 82 | \verbatim |
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[9] | 83 | g++ -lemon -I ~/lemon -L ~/lemon/lemon/.libs hello_lemon.cc -o hello_lemon |
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[6] | 84 | \endverbatim |
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| 85 | |
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| 86 | If everything has gone well, then our program prints out the followings. |
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| 87 | |
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| 88 | \verbatim |
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| 89 | Hello World! |
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| 90 | This is LEMON library here. We have a direceted graph. |
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| 91 | |
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| 92 | Nodes: 3 2 1 0 |
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| 93 | Arcs: (2,3) (1,3) (1,2) (0,2) (0,1) |
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| 94 | |
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| 95 | There is a map on the arcs (length): |
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| 96 | |
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| 97 | length(2,3)=10 |
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| 98 | length(1,3)=25 |
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| 99 | length(1,2)=5 |
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| 100 | length(0,2)=20 |
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| 101 | length(0,1)=10 |
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| 102 | \endverbatim |
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| 103 | |
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| 104 | You may note that iterating through the nodes and arcs is done in the |
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| 105 | reverse order compared to the creating order (the IDs are in decreasing |
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| 106 | order). |
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| 107 | This is due to implementation aspects, that may differ at other graph |
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| 108 | types, moreover it may be changed in the next releases. |
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| 109 | Thus you should not exploit this method in any way, you should not |
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| 110 | suppose anything about the iteration order. |
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| 111 | |
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| 112 | If you managed to compile and run this example code without any problems, |
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| 113 | you can go on reading this tutorial to get to know more features and tools |
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| 114 | of LEMON. |
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| 115 | Otherwise if you encountered problems that you did not manage to solve, |
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| 116 | do not hesitate to |
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| 117 | <a href="mailto:lemon-user@lemon.cs.elte.hu"><b>contact us</b></a>. |
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| 118 | |
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[10] | 119 | [TRAILER] |
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[3] | 120 | */ |
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[11] | 121 | } |
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