1 /********************************************************************
2 ********************************************************************
4 ** libhungarian by Cyrill Stachniss, 2004
6 ** Added and adapted to libFirm by Christian Wuerdig, 2006
8 ** Solving the Minimum Assignment Problem using the
11 ** ** This file may be freely copied and distributed! **
13 ** Parts of the used code was originally provided by the
14 ** "Stanford GraphGase", but I made changes to this code.
15 ** As asked by the copyright node of the "Stanford GraphGase",
16 ** I hereby proclaim that this file are *NOT* part of the
17 ** "Stanford GraphGase" distrubition!
19 ** This file is distributed in the hope that it will be useful,
20 ** but WITHOUT ANY WARRANTY; without even the implied
21 ** warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
24 ********************************************************************
25 ********************************************************************/
29 * @brief Solving the Minimum Assignment Problem using the Hungarian Method.
44 #include "hungarian.h"
46 #define INF (0x7FFFFFFF)
48 struct _hungarian_problem_t {
49 int num_rows; /**< number of rows */
50 int num_cols; /**< number of columns */
51 int **cost; /**< the cost matrix */
52 int width; /**< the width for cost matrix dumper */
53 int max_cost; /**< the maximal costs in the matrix */
54 int match_type; /**< PERFECT or NORMAL matching */
55 bitset_t *missing_left; /**< left side nodes having no edge to the right side */
56 bitset_t *missing_right; /**< right side nodes having no edge to the left side */
58 DEBUG_ONLY(firm_dbg_module_t *dbg);
61 static inline void *get_init_mem(struct obstack *obst, long sz) {
62 void *p = obstack_alloc(obst, sz);
67 static void hungarian_dump_f(FILE *f, int **C, int rows, int cols, int width) {
71 for (i = 0; i < rows; i++) {
73 for (j = 0; j < cols; j++) {
74 fprintf(f, "%*d", width, C[i][j]);
81 void hungarian_print_costmatrix(hungarian_problem_t *p) {
82 hungarian_dump_f(stderr, p->cost, p->num_rows, p->num_cols, p->width);
86 * Create the object and allocate memory for the data structures.
88 hungarian_problem_t *hungarian_new(int rows, int cols, int width, int match_type) {
90 hungarian_problem_t *p = XMALLOCZ(hungarian_problem_t);
92 FIRM_DBG_REGISTER(p->dbg, "firm.hungarian");
95 Is the number of cols not equal to number of rows ?
96 If yes, expand with 0 - cols / 0 - cols
98 rows = MAX(cols, rows);
101 obstack_init(&p->obst);
106 p->match_type = match_type;
109 In case of normal matching, we have to keep
110 track of nodes without edges to kill them in
111 the assignment later.
113 if (match_type == HUNGARIAN_MATCH_NORMAL) {
114 p->missing_left = bitset_obstack_alloc(&p->obst, rows);
115 p->missing_right = bitset_obstack_alloc(&p->obst, cols);
116 bitset_set_all(p->missing_left);
117 bitset_set_all(p->missing_right);
120 /* allocate space for cost matrix */
121 p->cost = (int **)get_init_mem(&p->obst, rows * sizeof(p->cost[0]));
122 for (i = 0; i < p->num_rows; i++)
123 p->cost[i] = (int *)get_init_mem(&p->obst, cols * sizeof(p->cost[0][0]));
129 * Prepare the cost matrix.
131 void hungarian_prepare_cost_matrix(hungarian_problem_t *p, int mode) {
134 if (mode == HUNGARIAN_MODE_MAXIMIZE_UTIL) {
135 for (i = 0; i < p->num_rows; i++) {
136 for (j = 0; j < p->num_cols; j++) {
137 p->cost[i][j] = p->max_cost - p->cost[i][j];
141 else if (mode == HUNGARIAN_MODE_MINIMIZE_COST) {
145 fprintf(stderr, "Unknown mode. Mode was set to HUNGARIAN_MODE_MINIMIZE_COST.\n");
149 * Set cost[left][right] to cost.
151 void hungarian_add(hungarian_problem_t *p, int left, int right, int cost) {
152 assert(p->num_rows > left && "Invalid row selected.");
153 assert(p->num_cols > right && "Invalid column selected.");
156 p->cost[left][right] = cost;
157 p->max_cost = MAX(p->max_cost, cost);
159 if (p->match_type == HUNGARIAN_MATCH_NORMAL) {
160 bitset_clear(p->missing_left, left);
161 bitset_clear(p->missing_right, right);
166 * Set cost[left][right] to 0.
168 void hungarian_remv(hungarian_problem_t *p, int left, int right) {
169 assert(p->num_rows > left && "Invalid row selected.");
170 assert(p->num_cols > right && "Invalid column selected.");
172 p->cost[left][right] = 0;
174 if (p->match_type == HUNGARIAN_MATCH_NORMAL) {
175 bitset_set(p->missing_left, left);
176 bitset_set(p->missing_right, right);
181 * Frees all allocated memory.
183 void hungarian_free(hungarian_problem_t* p) {
184 obstack_free(&p->obst, NULL);
191 int hungarian_solve(hungarian_problem_t* p, int *assignment, int *final_cost, int cost_threshold) {
192 int i, j, m, n, k, l, s, t, q, unmatched, cost;
206 col_mate = XMALLOCNZ(int, p->num_rows);
207 unchosen_row = XMALLOCNZ(int, p->num_rows);
208 row_dec = XMALLOCNZ(int, p->num_rows);
209 slack_row = XMALLOCNZ(int, p->num_rows);
211 row_mate = XMALLOCNZ(int, p->num_cols);
212 parent_row = XMALLOCNZ(int, p->num_cols);
213 col_inc = XMALLOCNZ(int, p->num_cols);
214 slack = XMALLOCNZ(int, p->num_cols);
216 memset(assignment, -1, m * sizeof(assignment[0]));
218 /* Begin subtract column minima in order to start with lots of zeros 12 */
219 DBG((p->dbg, LEVEL_1, "Using heuristic\n"));
221 for (l = 0; l < n; ++l) {
224 for (k = 1; k < m; ++k) {
225 if (p->cost[k][l] < s)
232 for (k = 0; k < m; ++k)
236 /* End subtract column minima in order to start with lots of zeros 12 */
238 /* Begin initial state 16 */
240 for (l = 0; l < n; ++l) {
247 for (k = 0; k < m; ++k) {
250 for (l = 1; l < n; ++l) {
251 if (p->cost[k][l] < s)
257 for (l = 0; l < n; ++l) {
258 if (s == p->cost[k][l] && row_mate[l] < 0) {
261 DBG((p->dbg, LEVEL_1, "matching col %d == row %d\n", l, k));
267 DBG((p->dbg, LEVEL_1, "node %d: unmatched row %d\n", t, k));
268 unchosen_row[t++] = k;
271 /* End initial state 16 */
273 /* Begin Hungarian algorithm 18 */
279 DBG((p->dbg, LEVEL_1, "Matched %d rows.\n", m - t));
284 /* Begin explore node q of the forest 19 */
288 for (l = 0; l < n; ++l) {
290 int del = p->cost[k][l] - s + col_inc[l];
292 if (del < slack[l]) {
299 DBG((p->dbg, LEVEL_1, "node %d: row %d == col %d -- row %d\n", t, row_mate[l], l, k));
300 unchosen_row[t++] = row_mate[l];
309 /* End explore node q of the forest 19 */
313 /* Begin introduce a new zero into the matrix 21 */
315 for (l = 0; l < n; ++l) {
316 if (slack[l] && slack[l] < s)
320 for (q = 0; q < t; ++q)
321 row_dec[unchosen_row[q]] += s;
323 for (l = 0; l < n; ++l) {
327 /* Begin look at a new zero 22 */
329 DBG((p->dbg, LEVEL_1, "Decreasing uncovered elements by %d produces zero at [%d, %d]\n", s, k, l));
330 if (row_mate[l] < 0) {
331 for (j = l + 1; j < n; ++j) {
339 DBG((p->dbg, LEVEL_1, "node %d: row %d == col %d -- row %d\n", t, row_mate[l], l, k));
340 unchosen_row[t++] = row_mate[l];
342 /* End look at a new zero 22 */
349 /* End introduce a new zero into the matrix 21 */
352 /* Begin update the matching 20 */
353 DBG((p->dbg, LEVEL_1, "Breakthrough at node %d of %d.\n", q, t));
359 DBG((p->dbg, LEVEL_1, "rematching col %d == row %d\n", l, k));
366 /* End update the matching 20 */
368 if (--unmatched == 0)
371 /* Begin get ready for another stage 17 */
373 for (l = 0; l < n; ++l) {
378 for (k = 0; k < m; ++k) {
379 if (col_mate[k] < 0) {
380 DBG((p->dbg, LEVEL_1, "node %d: unmatched row %d\n", t, k));
381 unchosen_row[t++] = k;
384 /* End get ready for another stage 17 */
388 /* Begin double check the solution 23 */
389 for (k = 0; k < m; ++k) {
390 for (l = 0; l < n; ++l) {
391 if (p->cost[k][l] < row_dec[k] - col_inc[l])
396 for (k = 0; k < m; ++k) {
398 if (l < 0 || p->cost[k][l] != row_dec[k] - col_inc[l])
402 for (k = l = 0; l < n; ++l) {
409 /* End double check the solution 23 */
411 /* End Hungarian algorithm 18 */
413 /* collect the assigned values */
414 for (i = 0; i < m; ++i) {
415 if (cost_threshold > 0 && p->cost[i][col_mate[i]] >= cost_threshold)
416 assignment[i] = -1; /* remove matching having cost > threshold */
418 assignment[i] = col_mate[i];
421 /* In case of normal matching: remove impossible ones */
422 if (p->match_type == HUNGARIAN_MATCH_NORMAL) {
423 for (i = 0; i < m; ++i) {
424 if (bitset_is_set(p->missing_left, i) || bitset_is_set(p->missing_right, col_mate[i]))
429 for (k = 0; k < m; ++k) {
430 for (l = 0; l < n; ++l) {
431 p->cost[k][l] = p->cost[k][l] - row_dec[k] + col_inc[l];
435 for (i = 0; i < m; ++i)
438 for (i = 0; i < n; ++i)
441 DBG((p->dbg, LEVEL_1, "Cost is %d\n", cost));