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/*
* Revision Control Information
*
* $Source$
* $Author$
* $Revision$
* $Date$
*
*/
#include "mincov_int.h"
/*
* check for:
*
* c1 c2 rest
* -- -- ---
* 1 1 0 0 0 0 <-- primary row
* 1 0 S1 <-- secondary row
* 0 1 T1
* 0 1 T2
* 0 1 Tn
* 0 0 R
*/
int
gimpel_reduce(A, select, weight, lb, bound, depth, stats, best)
sm_matrix *A;
solution_t *select;
int *weight;
int lb;
int bound;
int depth;
stats_t *stats;
solution_t **best;
{
register sm_row *prow, *save_sec;
register sm_col *c1, *c2;
register sm_element *p, *p1;
int c1_col_num, c2_col_num, primary_row_num, secondary_row_num;
int reduce_it;
reduce_it = 0;
for(prow = A->first_row; prow != 0; prow = prow->next_row) {
if (prow->length == 2) {
c1 = sm_get_col(A, prow->first_col->col_num);
c2 = sm_get_col(A, prow->last_col->col_num);
if (c1->length == 2) {
reduce_it = 1;
} else if (c2->length == 2) {
c1 = sm_get_col(A, prow->last_col->col_num);
c2 = sm_get_col(A, prow->first_col->col_num);
reduce_it = 1;
}
if (reduce_it) {
primary_row_num = prow->row_num;
secondary_row_num = c1->first_row->row_num;
if (secondary_row_num == primary_row_num) {
secondary_row_num = c1->last_row->row_num;
}
break;
}
}
}
if (reduce_it) {
c1_col_num = c1->col_num;
c2_col_num = c2->col_num;
save_sec = sm_row_dup(sm_get_row(A, secondary_row_num));
sm_row_remove(save_sec, c1_col_num);
for(p = c2->first_row; p != 0; p = p->next_row) {
if (p->row_num != primary_row_num) {
/* merge rows S1 and T */
for(p1 = save_sec->first_col; p1 != 0; p1 = p1->next_col) {
(void) sm_insert(A, p->row_num, p1->col_num);
}
}
}
sm_delcol(A, c1_col_num);
sm_delcol(A, c2_col_num);
sm_delrow(A, primary_row_num);
sm_delrow(A, secondary_row_num);
stats->gimpel_count++;
stats->gimpel++;
*best = sm_mincov(A, select, weight, lb-1, bound-1, depth, stats);
stats->gimpel--;
if (*best != NIL(solution_t)) {
/* is secondary row covered ? */
if (sm_row_intersects(save_sec, (*best)->row)) {
/* yes, actually select c2 */
solution_add(*best, weight, c2_col_num);
} else {
solution_add(*best, weight, c1_col_num);
}
}
sm_row_free(save_sec);
return 1;
} else {
return 0;
}
}
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