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#include "espresso.h"
#include "mincov_int.h"
static int visit_col();
static void
copy_row(A, prow)
register sm_matrix *A;
register sm_row *prow;
{
register sm_element *p;
for(p = prow->first_col; p != 0; p = p->next_col) {
(void) sm_insert(A, p->row_num, p->col_num);
}
}
static int
visit_row(A, prow, rows_visited, cols_visited)
sm_matrix *A;
sm_row *prow;
int *rows_visited;
int *cols_visited;
{
sm_element *p;
sm_col *pcol;
if (! prow->flag) {
prow->flag = 1;
(*rows_visited)++;
if (*rows_visited == A->nrows) {
return 1;
}
for(p = prow->first_col; p != 0; p = p->next_col) {
pcol = sm_get_col(A, p->col_num);
if (! pcol->flag) {
if (visit_col(A, pcol, rows_visited, cols_visited)) {
return 1;
}
}
}
}
return 0;
}
static int
visit_col(A, pcol, rows_visited, cols_visited)
sm_matrix *A;
sm_col *pcol;
int *rows_visited;
int *cols_visited;
{
sm_element *p;
sm_row *prow;
if (! pcol->flag) {
pcol->flag = 1;
(*cols_visited)++;
if (*cols_visited == A->ncols) {
return 1;
}
for(p = pcol->first_row; p != 0; p = p->next_row) {
prow = sm_get_row(A, p->row_num);
if (! prow->flag) {
if (visit_row(A, prow, rows_visited, cols_visited)) {
return 1;
}
}
}
}
return 0;
}
int
sm_block_partition(A, L, R)
sm_matrix *A;
sm_matrix **L, **R;
{
int cols_visited, rows_visited;
register sm_row *prow;
register sm_col *pcol;
/* Avoid the trivial case */
if (A->nrows == 0) {
return 0;
}
/* Reset the visited flags for each row and column */
for(prow = A->first_row; prow != 0; prow = prow->next_row) {
prow->flag = 0;
}
for(pcol = A->first_col; pcol != 0; pcol = pcol->next_col) {
pcol->flag = 0;
}
cols_visited = rows_visited = 0;
if (visit_row(A, A->first_row, &rows_visited, &cols_visited)) {
/* we found all of the rows */
return 0;
} else {
*L = sm_alloc();
*R = sm_alloc();
for(prow = A->first_row; prow != 0; prow = prow->next_row) {
if (prow->flag) {
copy_row(*L, prow);
} else {
copy_row(*R, prow);
}
}
return 1;
}
}
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