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    /*
     *  grafo - graph editor
     *  Copyright (c) 2008
     *      Ulisses Cordeiro Pereira <ulisses@cordeiropereira.com.br>
     *
     *  This program 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 2 of the License, or
     *  (at your option) any later version.
     *
     *  This program 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 (file COPYING).
     */

    /* ********************** */
    /* * selectoddexample.c * */
    /* ********************** */

    /* Plugin example: This program does not compute anything useful.
     * It is an example of how to use the "step by step" structure.
     * The odd vertex and edges between odd vertex will be highlighted in the GRAFO
     * interface.
     *
     */

    /* Plugin example: Select odd */

    /* C language headers */
    #include <stdio.h>
    #include <stdlib.h>

    /* Here the GRAFO headers */
    /* Add plugins information */
    #include "../pgin.h"

    /* Add graph struct information */
    #include "../graph.h"

    /* Add step by step struct information */
    #include "../step.h"

    /* Mandatory function pgin_info */
    Pgin *pgin_info(void);

    /* algorithm function */
    int SelectOdd(Graph *G, char *mess, int indx, List *arc_edges, List *verts);

    /* Others functions */

    /* The pgin_info() function should always be present. GRAFO will call
     * it to get the plugin information.
     */
    Pgin *pgin_info(void){
    Pgin *pgin;

        /* Alocate space for SelectOdd and PGIN_LIST_END */
        pgin = (Pgin *) malloc(2 * sizeof(Pgin));

        /* Includes SelectOdd as the first algorithm of plugin */
        pgin[0].type = PGIN_STEP_ALG;
        pgin[0].label = "Select odd";
        pgin[0].name = "SelectOdd";
        pgin[0].flags = 0;

        /* It indicates the end of the list of algorithms */
        pgin[1].type = PGIN_LIST_END;
        pgin[1].label = 0;
        pgin[1].name = 0;
        pgin[1].flags = 0;

        return pgin;
    }

    /* This is the plugin's main function */
    int SelectOdd(Graph *G, char *mess, int indx, List *arc_edges, List *verts) {
    SEdge E; /* Single Edge */
    Node N;
    int i, j,oddvertex;

        /* Test if graph is empty */
        if (G->size < 1) {
            sprintf(mess, "%s", "Empty graph!");
            return 1;
        }

        /* Set to False (0) the property 'mark' in all vertices */
        ClearMarkedVerts(G);

        /* Add first step - No highlights */
        AddStep(G, arc_edges, verts);

        /* Find and mark oddvertex */
        oddvertex = 0;
        for (i = 1; i < G->size; i++) {

            /* Check if i is a odd number */
            if ((i % 2)) {
                /* Mark the vertex for future use */
                G->vertex[i].mark = 1;
                oddvertex = i;

                /* Place oddvertex in the Node */
                N = MakeNode(&oddvertex, sizeof(int));

                /* Place the node in the list of "special vertex" */
                InsertNode(verts, N);

                /* Add new step - Save highlight vertex */
                AddStep(G, arc_edges, verts);
            }
        }

        /* Set to False (0) the property 'mark' in all vertices */
        ClearMarkedEdges(G);

        /* Find the odd vertex adjacent with other odd vertex */
        for (i = 0; i < G->size; i++) {
            for (j = 0; j < G->size; j++) {

                    /* Avoid saving the step [j,i] because [i,j] have been saved */
                if (!G->prop[j][i].mark && \
                    /* True if vertex[i] is adjacent vertex[j] */
                    G->edge[i][j] && \
                    /* True if vertex[i] is a odd vertex */
                    G->vertex[i].mark && \
                    /* True if vertex[j] is a odd vertex */
                    G->vertex[j].mark) {

                    /* Mark the edge for future use */
                    G->prop[i][j].mark = 1;

                    /* Assign odd vertex adjacent with other odd vertex in a single edge */
                    E.u = i;
                    E.v = j;

                    /* Place the "single edge" in the Node */
                    N = MakeNode(&E, sizeof(SEdge));

                    /* Place the node in the list of "special edges" */
                    InsertNode(arc_edges, N);

                    /* Add new step - Save highlight edge */
                    AddStep(G, arc_edges, verts);
                }
            }
        }

        return 1;
    }

    /* ******* */
    /* * End * */
    /* ******* */