/* glpnet05.c (Goldfarb's maximum flow problem generator) */

/***********************************************************************

*  This code is part of GLPK (GNU Linear Programming Kit).

*

*  This code is a modified version of the program RMFGEN, a maxflow

*  problem generator developed by D.Goldfarb and M.Grigoriadis, and

*  originally implemented by Tamas Badics <badics@rutcor.rutgers.edu>.

*  The original code is publically available on the DIMACS ftp site at:

*  <ftp://dimacs.rutgers.edu/pub/netflow/generators/network/genrmf>.

*

*  All changes concern only the program interface, so this modified

*  version produces exactly the same instances as the original version.

*

*  Changes were made by Andrew Makhorin <mao@gnu.org>.

*

*  GLPK 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 of the License, or

*  (at your option) any later version.

*

*  GLPK 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 GLPK. If not, see <http://www.gnu.org/licenses/>.

***********************************************************************/

#include "glpapi.h"

#include "glprng.h"

/***********************************************************************

*  NAME

*

*  glp_rmfgen - Goldfarb's maximum flow problem generator

*

*  SYNOPSIS

*

*  int glp_rmfgen(glp_graph *G, int *s, int *t, int a_cap,

*     const int parm[1+5]);

*

*  DESCRIPTION

*

*  The routine glp_rmfgen is a maximum flow problem generator developed

*  by D.Goldfarb and M.Grigoriadis.

*

*  The parameter G specifies the graph object, to which the generated

*  problem data have to be stored. Note that on entry the graph object

*  is erased with the routine glp_erase_graph.

*

*  The pointer s specifies a location, to which the routine stores the

*  source node number. If s is NULL, the node number is not stored.

*

*  The pointer t specifies a location, to which the routine stores the

*  sink node number. If t is NULL, the node number is not stored.

*

*  The parameter a_cap specifies an offset of the field of type double

*  in the arc data block, to which the routine stores the arc capacity.

*  If a_cap < 0, the capacity is not stored.

*

*  The array parm contains description of the network to be generated:

*

*  parm[0]  not used

*  parm[1]  (seed)   random number seed (a positive integer)

*  parm[2]  (a)      frame size

*  parm[3]  (b)      depth

*  parm[4]  (c1)     minimal arc capacity

*  parm[5]  (c2)     maximal arc capacity

*

*  RETURNS

*

*  If the instance was successfully generated, the routine glp_netgen

*  returns zero; otherwise, if specified parameters are inconsistent,

*  the routine returns a non-zero error code.

*

*  COMMENTS

*

*  The generated network is as follows. It has b pieces of frames of

*  size a * a. (So alltogether the number of vertices is a * a * b)

*

*  In each frame all the vertices are connected with their neighbours

*  (forth and back). In addition the vertices of a frame are connected

*  one to one with the vertices of next frame using a random permutation

*  of those vertices.

*

*  The source is the lower left vertex of the first frame, the sink is

*  the upper right vertex of the b'th frame.

*

*                    t

*           +-------+

*           |      .|

*           |     . |

*        /  |    /  |

*       +-------+/ -+ b

*       |    |  |/.

*     a |   -v- |/

*       |    |  |/

*       +-------+ 1

*      s    a

*

*  The capacities are randomly chosen integers from the range of [c1,c2]

*  in the case of interconnecting edges, and c2 * a * a for the in-frame

*  edges.

*

*  REFERENCES

*

*  D.Goldfarb and M.D.Grigoriadis, "A computational comparison of the

*  Dinic and network simplex methods for maximum flow." Annals of Op.

*  Res. 13 (1988), pp. 83-123.

*

*  U.Derigs and W.Meier, "Implementing Goldberg's max-flow algorithm:

*  A computational investigation." Zeitschrift fuer Operations Research

*  33 (1989), pp. 383-403. */

typedef struct VERTEX

{     struct EDGE **edgelist;

      /* Pointer to the list of pointers to the adjacent edges.

         (No matter that to or from edges) */

      struct EDGE **current;

      /* Pointer to the current edge */

      int degree;

      /* Number of adjacent edges (both direction) */

      int index;

} vertex;

typedef struct EDGE

{     int from;

      int to;

      int cap;

      /* Capacity */

} edge;

typedef struct NETWORK

{     struct NETWORK *next, *prev;

      int vertnum;

      int edgenum;

      vertex *verts;

      /* Vertex array[1..vertnum] */

      edge *edges;

      /* Edge array[1..edgenum] */

      int source;

      /* Pointer to the source */

      int sink;

      /* Pointer to the sink */

} network;

struct csa

{     /* common storage area */

      glp_graph *G;

      int *s, *t, a_cap;

      RNG *rand;

      network *N;

      int *Parr;

      int A, AA, C2AA, Ec;

};

#define G      (csa->G)

#define s      (csa->s)

#define t      (csa->t)

#define a_cap  (csa->a_cap)

#define N      (csa->N)

#define Parr   (csa->Parr)

#define A      (csa->A)

#define AA     (csa->AA)

#define C2AA   (csa->C2AA)

#define Ec     (csa->Ec)

#undef random

#define random(A) (int)(rng_unif_01(csa->rand) * (double)(A))

#define RANDOM(A, B) (int)(random((B) - (A) + 1) + (A))

#define sgn(A) (((A) > 0) ? 1 : ((A) == 0) ? 0 : -1)

static void make_edge(struct csa *csa, int from, int to, int c1, int c2)

{     Ec++;

      N->edges[Ec].from = from;

      N->edges[Ec].to = to;

      N->edges[Ec].cap = RANDOM(c1, c2);

      return;

}

static void permute(struct csa *csa)

{     int i, j, tmp;

      for (i = 1; i < AA; i++)

      {  j = RANDOM(i, AA);

         tmp = Parr[i];

         Parr[i] = Parr[j];

         Parr[j] = tmp;

      }

      return;

}

static void connect(struct csa *csa, int offset, int cv, int x1, int y1)

{     int cv1;

      cv1 = offset + (x1 - 1) * A + y1;

      Ec++;

      N->edges[Ec].from = cv;

      N->edges[Ec].to = cv1;

      N->edges[Ec].cap = C2AA;

      return;

}

static network *gen_rmf(struct csa *csa, int a, int b, int c1, int c2)

{     /* generates a network with a*a*b nodes and 6a*a*b-4ab-2a*a edges

         random_frame network:

         Derigs & Meier, Methods & Models of OR (1989), 33:383-403 */

      int x, y, z, offset, cv;

      A = a;

      AA = a * a;

      C2AA = c2 * AA;

      Ec = 0;

      N = (network *)xmalloc(sizeof(network));

      N->vertnum = AA * b;

      N->edgenum = 5 * AA * b - 4 * A * b - AA;

      N->edges = (edge *)xcalloc(N->edgenum + 1, sizeof(edge));

      N->source = 1;

      N->sink = N->vertnum;

      Parr = (int *)xcalloc(AA + 1, sizeof(int));

      for (x = 1; x <= AA; x++)

         Parr[x] = x;

      for (z = 1; z <= b; z++)

      {  offset = AA * (z - 1);

         if (z != b)

            permute(csa);

         for (x = 1; x <= A; x++)

         {  for (y = 1; y <= A; y++)

            {  cv = offset + (x - 1) * A + y;

               if (z != b)

                  make_edge(csa, cv, offset + AA + Parr[cv - offset],

                     c1, c2); /* the intermediate edges */

               if (y < A)

                  connect(csa, offset, cv, x, y + 1);

               if (y > 1)

                  connect(csa, offset, cv, x, y - 1);

               if (x < A)

                  connect(csa, offset, cv, x + 1, y);

               if (x > 1)

                  connect(csa, offset, cv, x - 1, y);

            }

         }

      }

      xfree(Parr);

      return N;

}

static void print_max_format(struct csa *csa, network *n, char *comm[],

      int dim)

{     /* prints a network heading with dim lines of comments (no \n

         needs at the ends) */

      int i, vnum, e_num;

      edge *e;

      vnum = n->vertnum;

      e_num = n->edgenum;

      if (G == NULL)

      {  for (i = 0; i < dim; i++)

            xprintf("c %s\n", comm[i]);

         xprintf("p max %7d %10d\n", vnum, e_num);

         xprintf("n %7d s\n", n->source);

         xprintf("n %7d t\n", n->sink);

      }

      else

      {  glp_add_vertices(G, vnum);

         if (s != NULL) *s = n->source;

         if (t != NULL) *t = n->sink;

      }

      for (i = 1; i <= e_num; i++)

      {  e = &n->edges[i];

         if (G == NULL)

            xprintf("a %7d %7d %10d\n", e->from, e->to, (int)e->cap);

         else

         {  glp_arc *a = glp_add_arc(G, e->from, e->to);

            if (a_cap >= 0)

            {  double temp = (double)e->cap;

               memcpy((char *)a->data + a_cap, &temp, sizeof(double));

            }

         }

      }

      return;

}

static void gen_free_net(network *n)

{     xfree(n->edges);

      xfree(n);

      return;

}

int glp_rmfgen(glp_graph *G_, int *_s, int *_t, int _a_cap,

      const int parm[1+5])

{     struct csa _csa, *csa = &_csa;

      network *n;

      char comm[10][80], *com1[10];

      int seed, a, b, c1, c2, ret;

      G = G_;

      s = _s;

      t = _t;

      a_cap = _a_cap;

      if (G != NULL)

      {  if (a_cap >= 0 && a_cap > G->a_size - (int)sizeof(double))

           xerror("glp_rmfgen: a_cap = %d; invalid offset\n", a_cap);

      }

      seed = parm[1];

      a = parm[2];

      b = parm[3];

      c1 = parm[4];

      c2 = parm[5];

      if (!(seed > 0 && 1 <= a && a <= 1000 && 1 <= b && b <= 1000 &&

            0 <= c1 && c1 <= c2 && c2 <= 1000))

      {  ret = 1;

         goto done;

      }

      if (G != NULL)

      {  glp_erase_graph(G, G->v_size, G->a_size);

         glp_set_graph_name(G, "RMFGEN");

      }

      csa->rand = rng_create_rand();

      rng_init_rand(csa->rand, seed);

      n = gen_rmf(csa, a, b, c1, c2);

      sprintf(comm[0], "This file was generated by genrmf.");

      sprintf(comm[1], "The parameters are: a: %d b: %d c1: %d c2: %d",

         a, b, c1, c2);

      com1[0] = comm[0];

      com1[1] = comm[1];

      print_max_format(csa, n, com1, 2);

      gen_free_net(n);

      rng_delete_rand(csa->rand);

      ret = 0;

done: return ret;

}

/**********************************************************************/

#if 0

int main(int argc, char *argv[])

{     int seed, a, b, c1, c2, i, parm[1+5];

      seed = 123;

      a = b = c1 = c2 = -1;

      for (i = 1; i < argc; i++)

      {  if (strcmp(argv[i], "-seed") == 0)

            seed = atoi(argv[++i]);

         else if (strcmp(argv[i], "-a") == 0)

            a = atoi(argv[++i]);

         else if (strcmp(argv[i], "-b") == 0)

            b = atoi(argv[++i]);

         else if (strcmp(argv[i], "-c1") == 0)

            c1 = atoi(argv[++i]);

         else if (strcmp(argv[i], "-c2") == 0)

            c2 = atoi(argv[++i]);

      }

      if (a < 0 || b < 0 || c1 < 0 || c2 < 0)

      {  xprintf("Usage:\n");

         xprintf("genrmf [-seed seed] -a frame_size -b depth\n");

         xprintf("        -c1 cap_range1 -c2 cap_range2\n");

      }

      else

      {  parm[1] = seed;

         parm[2] = a;

         parm[3] = b;

         parm[4] = c1;

         parm[5] = c2;

         glp_rmfgen(NULL, NULL, NULL, 0, parm);

      }

      return 0;

}

#endif

/* eof */