7 * (c) 2003 Mark Wooding
10 /*----- Licensing notice --------------------------------------------------*
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; either version 2 of the License, or
15 * (at your option) any later version.
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software Foundation,
24 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
27 /*----- Header files ------------------------------------------------------*/
39 /*----- Static variables --------------------------------------------------*/
41 #define INF ((unsigned long)-1)
43 /*----- Utility functions -------------------------------------------------*/
45 static int err(Tcl_Interp *ti, /*const*/ char *p)
47 Tcl_SetResult(ti, p, TCL_STATIC);
53 * Arguments: @Tcl_Interp *ti@ = interpreter to leave errors in
54 * @vec *v@ = pointer to input adjacency matrix
55 * @unsigned long *tt@ = pointer to output adjacency matrix
56 * @size_t *nn@ = where to put the table size
58 * Returns: Tcl return code.
60 * Use: Imports an adjacency matrix.
63 static int import(Tcl_Interp *ti, vec *v, unsigned long **tt, size_t *nn)
69 /* --- Check the table is well-formed --- */
72 return (err(ti, "adjacency matrix must be two-dimensional"));
73 if (v->dim[0].lo != 0 || v->dim[1].lo || v->dim[0].hi != v->dim[1].hi)
74 return (err(ti, "adjacency matrix must be square and zero-origin"));
75 n = *nn = v->dim[0].hi;
77 /* --- Copy the data over --- */
81 t = (void *)Tcl_Alloc(n * sizeof(*t));
82 for (i = 0; i < n; i++) {
84 if (Tcl_GetLongFromObj(ti, v->v[i], &l) != TCL_OK) {
88 t[i] = l >= 0 ? l : INF;
96 * Arguments: @Tcl_Interp *ti@ = interpreter to create output vector
97 * @unsigned long *t@ = pointer to table
98 * @size_t n@ = size of the table
100 * Returns: A pointer to the vector, or null.
102 * Use: Exports an adjacency matrix.
105 static vec *export(Tcl_Interp *ti, unsigned long *t, size_t n)
112 b[0].lo = b[1].lo = 0;
113 b[0].hi = b[1].hi = n;
114 if ((v = vec_create(ti, 2, b, 0)) == 0)
116 o = Tcl_NewLongObj(-1);
118 for (i = 0; i < v->n; i++) {
119 v->v[i] = t[i] == INF ? o : Tcl_NewLongObj(t[i]);
120 Tcl_IncrRefCount(v->v[i]);
126 /*----- Floyd-Warshall all-points shortest path ---------------------------*/
128 /* --- @graph-shortest-path VEC@ --- *
130 * Returns a pair of vectors containing, respectively, the shortest path
131 * length and the successor element in the shortest path. If you say
133 * destructure {len path} [graph-shortest-path $v]
135 * then [$len get I J] is the shortest path length from node I to node J, and
136 * [$path get I J] is the first hop on that shortest path. (To compute the
137 * entire path, set K to be that first hop; the next hop is then [$path get K
140 * The adjacency matrix is given in VEC: negative entries indicate no path;
141 * nonnegative entries are weights. All entries must be integers.
144 static int cmd_shortestpath(ClientData cd, Tcl_Interp *ti,
145 int objc, Tcl_Obj *const *objv)
147 vec *v, *lv = 0, *pv = 0;
149 unsigned long *a = 0, *p = 0;
152 /* --- Read in the arguments --- */
155 err(ti, "usage: graph-shortest-path VEC");
158 if ((v = vec_find(ti, objv[1])) == 0 || import(ti, v, &a, &n) != TCL_OK)
161 /* --- Set up the path table --- */
163 p = (void *)Tcl_Alloc(n * n * sizeof(*p));
164 for (i = 0; i < n; i++) {
165 for (j = 0; j < n; j++)
170 /* --- Do the main algorithm --- *
172 * Not so hard. Just brute force and ignorance.
175 for (k = 0; k < n; k++) {
176 for (i = 0; i < n; i++) {
177 for (j = 0; j < n; j++) {
178 if (a[i * n + k] != INF && a[k * n + j] != INF &&
179 a[i * n + k] + a[k * n + j] < a[i * n + j]) {
180 a[i * n + j] = a[i * n + k] + a[k * n + j];
181 p[i * n + j] = p[i * n + k];
187 /* --- Wrap up --- */
189 if ((lv = export(ti, a, n)) == 0 || (pv = export(ti, p, n)) == 0)
191 o = Tcl_NewListObj(0, 0);
192 Tcl_ListObjAppendElement
193 (ti, o, Tcl_NewStringObj(Tcl_GetCommandName(ti, lv->c), -1));
194 Tcl_ListObjAppendElement
195 (ti, o, Tcl_NewStringObj(Tcl_GetCommandName(ti, pv->c), -1));
196 Tcl_SetObjResult(ti, o);
202 if (a) Tcl_Free((void *)a);
203 if (p) Tcl_Free((void *)p);
204 if (lv) vec_destroy(ti, lv);
205 if (pv) vec_destroy(ti, pv);
209 /*----- Travelling Salesman Problem ---------------------------------------*/
211 /* --- @rrange@ --- *
213 * Arguments: @size_t max@ = maximum number wanted
215 * Returns: An integer uniformly distributed on %$[0, max)$%.
218 static size_t rrange(size_t max)
231 /* --- @graph-travelling-salesman [-OPTIONS] ADJ LIST@ --- *
233 * Solves the Travelling Salesman Problem approximately. Returns a list
234 * containing (firstly) the cost of the computed route, and secondly the
235 * route itself. Only the nodes in LIST are considered. The OPTIONS affect
236 * the algorithm in various ways.
238 * -cool FACTOR Cooling factor. Default is 1.001. Must be greater
239 * than 1 for the simulated annealing to work.
241 * -dead COUNT Give up after COUNT cycles with no improvement.
244 * -inner COUNT Perform COUNT loops each cooling cycle. Default is
247 * -temp TEMP Set the initial temperature to TEMP. Default is not
248 * very helpful. Initial setting should be well above
249 * the maximum cost increase from a cycle.
251 * -cycle / -nocycle If -cycle is set, solve the classical problem of
252 * finding a minimal cyclic path. If -nocycle is set,
253 * then start at the first node in LIST, and minimize a
254 * tour without caring where the end goes. The default
258 static int cmd_tsp(ClientData cd, Tcl_Interp *ti,
259 int objc, Tcl_Obj *const *objv)
261 /* --- Initial algorithm parameters --- */
269 /* --- Other variables --- */
272 unsigned long *a = 0;
275 size_t *r = 0, *r_best = 0;
276 unsigned long c_best = 0, c_curr, c;
281 Tcl_Obj *o, *o2, **oo;
283 /* --- Parse the command line --- */
285 for (i = 1; i < objc; i++) {
287 char *p = Tcl_GetStringFromObj(objv[i], &len);
288 if (strcmp(p, "-cool") == 0) {
289 i++; if (i >= objc) goto args;
290 if (Tcl_GetDoubleFromObj(ti, objv[i], &cool) != TCL_OK)
293 err(ti, "cooling factor must be > 1");
296 } else if (strcmp(p, "-temp") == 0) {
297 i++; if (i >= objc) goto args;
298 if (Tcl_GetDoubleFromObj(ti, objv[i], &temp) != TCL_OK)
301 err(ti, "initial temperature must be > 0");
304 } else if (strcmp(p, "-inner") == 0) {
305 i++; if (i >= objc) goto args;
306 if (Tcl_GetLongFromObj(ti, objv[i], &inner) != TCL_OK)
309 err(ti, "inner loop count must be > 0");
312 } else if (strcmp(p, "-dead") == 0) {
313 i++; if (i >= objc) goto args;
314 if (Tcl_GetLongFromObj(ti, objv[i], &dead) != TCL_OK)
317 err(ti, "dead cycles count must be > 0");
320 } else if (strcmp(p, "-cycle") == 0)
322 else if (strcmp(p, "-nocycle") == 0)
324 else if (strcmp(p, "--") == 0) {
326 } else if (*p != '-')
329 err(ti, "bad option for graph-travelling-salesman");
334 /* --- Check the rest --- */
337 err(ti, "usage: graph-travelling-salesman [-OPTIONS] ADJ LIST");
340 if ((v = vec_find(ti, objv[i])) == 0 || import(ti, v, &a, &n) != TCL_OK)
342 if (Tcl_ListObjGetElements(ti, objv[i + 1], &nn, &oo) != TCL_OK)
347 r = (void *)Tcl_Alloc(nn * sizeof(*r));
348 r_best = (void *)Tcl_Alloc(nn * sizeof(*r_best));
349 for (i = 0; i < nn; i++) {
351 if (Tcl_GetLongFromObj(ti, oo[i], &l) != TCL_OK)
353 if (l < 0 || l >= n) {
354 err(ti, "node index out of range");
360 /* --- The one and two node problems are trivial --- *
362 * Avoiding these prevents us from having to mess with special cases later.
366 memcpy(r_best, r, nn * sizeof(*r));
368 c_best = a[r[0] * n + r[0]];
370 c_best = a[r[0] * n + r[1]];
374 /* --- Randomize the initial vector --- *
376 * If we're not cycling, then nail the first item in place.
379 for (i = cycle ? 0 : 1; i < nn; i++) {
381 t = r[i]; r[i] = r[i + j]; r[i + j] = t;
384 /* --- Compute the initial cost --- *
386 * If we're not cycling, don't close off at the end. The easiest way to do
387 * that is to start at the end. There are at least three elements.
390 if (cycle) { j = 0; i = nn - 1; }
391 else { j = nn - 1; i = j - 1; }
394 c += a[r[i] * n + r[j]];
401 /* printf("*** initial cost = %lu; n = %u; nn = %u\n", c, n, nn); */
403 memcpy(r_best, r, nn * sizeof(*r));
405 /* --- Embark on the main loop --- */
410 for (ii = inner; ii; ii--) {
411 size_t i, j, ilo, ihi, jlo, jhi;
413 /* --- Decide on a change to make --- *
415 * We just swap two nodes around on the path. This is simple and seems
416 * to be effective. Don't allow the first node to be moved if we're
424 i = rrange(nn - 1) + 1;
425 j = rrange(nn - 1) + 1;
428 /* --- Compute the change in cost --- *
430 * Since we're only swapping two nodes, we can work out the change
431 * without rescanning the entire path, by just looking at the local
436 continue; /* No change */
437 if (j < i) { t = i; i = j; j = t; }
438 ilo = (i + nn - 1) % nn; ihi = (i + 1) % nn;
439 jlo = (j + nn - 1) % nn; jhi = (j + 1) % nn;
444 /* --- This is where the algorithms differ --- *
446 * If we're producing a cycle, then we need the cost function to wrap
447 * around here. Otherwise, it hits a barrier, and the last node only
448 * has a partial effect.
453 c -= (a[r[jlo] * n + r[j]] +
455 a[r[i] * n + r[ihi]]);
456 c += (a[r[jlo] * n + r[i]] +
458 a[r[j] * n + r[ihi]]);
462 c -= a[r[ilo] * n + r[i]] + a[r[i] * n + r[j]];
463 c += a[r[ilo] * n + r[j]] + a[r[j] * n + r[i]];
465 c -= (a[r[ilo] * n + r[i]] +
466 a[r[i] * n + r[ihi]] +
467 a[r[jlo] * n + r[j]]);
468 c += (a[r[ilo] * n + r[j]] +
469 a[r[j] * n + r[ihi]] +
470 a[r[jlo] * n + r[i]]);
475 /* --- Usual case --- *
477 * This splits into two subcases, depending on whether the areas
483 c -= (a[r[ilo] * n + r[i]] +
485 a[r[j] * n + r[jhi]]);
486 c += (a[r[ilo] * n + r[j]] +
488 a[r[i] * n + r[jhi]]);
490 c -= (a[r[ilo] * n + r[i]] +
491 a[r[i] * n + r[ihi]] +
492 a[r[jlo] * n + r[j]] +
493 a[r[j] * n + r[jhi]]);
494 c += (a[r[ilo] * n + r[j]] +
495 a[r[j] * n + r[ihi]] +
496 a[r[jlo] * n + r[i]] +
497 a[r[i] * n + r[jhi]]);
501 #ifdef PARANOID_CHECKING /* Turn this on to check the shortcut */
505 if (cycle) { jj = 0; ii = nn - 1; }
506 else { jj = nn - 1; ii = jj - 1; }
508 t = r[i]; r[i] = r[j]; r[j] = t;
510 cc += a[r[ii] * n + r[jj]];
516 t = r[i]; r[i] = r[j]; r[j] = t;
518 printf("i = %u; j = %u; c = %lu; cc = %lu\n", i, j, c, cc);
524 /* --- Decide what to do --- */
527 rrange(65536) >= (size_t)(exp(((double)c_curr -
528 (double)c)/temp) * 65536))
531 /* --- Accept the change --- */
536 t = r[i]; r[i] = r[j]; r[j] = t;
537 if (c_curr < c_best) {
539 /* printf("*** new best = %lu\n", c_best); */
540 memcpy(r_best, r, nn * sizeof(*r));
553 o = Tcl_NewListObj(0, 0);
554 o2 = Tcl_NewListObj(0, 0);
555 Tcl_ListObjAppendElement(ti, o, Tcl_NewLongObj(c_best));
556 for (i = 0; i < nn; i++)
557 Tcl_ListObjAppendElement(ti, o2, Tcl_NewLongObj(r_best[i]));
558 Tcl_ListObjAppendElement(ti, o, o2);
559 Tcl_SetObjResult(ti, o);
562 /* --- Tidy up --- */
565 if (a) Tcl_Free((void *)a);
566 if (r) Tcl_Free((void *)r);
567 if (r_best) Tcl_Free((void *)r_best);
571 err(ti, "missing argument for option");
575 /*----- Initialization ----------------------------------------------------*/
577 int Graph_SafeInit(Tcl_Interp *ti)
579 static const struct cmd {
580 /*const*/ char *name;
581 Tcl_ObjCmdProc *proc;
583 { "graph-shortest-path", cmd_shortestpath },
584 { "graph-travelling-salesman", cmd_tsp },
589 if (Tcl_PkgRequire(ti, "vector", "1.0.0", 0) == 0)
591 for (c = cmds; c->name; c++)
592 Tcl_CreateObjCommand(ti, c->name, c->proc, 0, 0);
593 if (Tcl_PkgProvide(ti, "graph", "1.0.0"))
598 int Graph_Init(Tcl_Interp *ti)
600 return (Graph_SafeInit(ti));
603 /*----- That's all, folks -------------------------------------------------*/