opm-simulators/dfs.c
Bård Skaflestad 3e76680f4d Silence compiler by adding prototype for dfs() (i.e., #include
"dfs.h").  Also, don't require build(er|system) to always #define
  the preprocessing symbol "TEST" (to a zero or non-zero value).
2010-08-20 21:44:49 +00:00

109 lines
2.4 KiB
C

/*======================================================================
File: dfs.c
Created: Tue May 6 09:27:26 2008
Author: Jostein R. Natvig <Jostein.R.Natvig@sintef.no>
Revision: $Id$
====================================================================*/
#include <assert.h>
#include "dfs.h"
/*
* Assign color (nonnegative number) to each connected component of graph
*/
void dfs (int size, int *ia, int *ja, int *ncolors, int *color, int* work)
{
int i, c;
enum {UNVISITED = -1, VISITED = -2};
int *stack = work;
int *count = work + size;
int *bottom = stack;
*ncolors = 0; /* colors are nonnegative */
for (i=0; i<size; ++i) {
color [i] = UNVISITED;
count [i] = ia[i+1]-ia[i];
}
/* Push seeds on stack */
for (i=0; i<size; ++i) {
if(color[i] >= 0) { /* FINISHED */
continue;
}
*stack++ = i; /* push i */
color[i] = VISITED;
while ( stack != bottom ) {
c = *(stack-1); /* peek */
if (count[c] > 0){
int child = ja[ia[c] + count[c]-1];
count[c]--;
if (color[child] == UNVISITED) {
*stack++ = child;
color[c] = VISITED;
}
} else {
color[c] = *ncolors;
--stack; /* pop c */
}
}
++*ncolors;
}
}
#if defined(TEST) && TEST
#include <stdlib.h>
#include <stdio.h>
/* Test code. Reads a sparse matrix from a file specified on the */
/* command line with file format "m n\n i1 j1 v1\n i2 j2 v2\n ...". */
/* Computes reorder sequence */
int main (int argc, char *argv [])
{
int *color, *work;
int j, ncolors;
#if 0
int size = 8;
int ia[] = {0, 1, 2, 4, 5, 5, 7, 7, 8};
int ja[] = {1, 2, 0, 3, 4, 5, 6, 6};
#else
int size = 3;
int ia[] = {0,2,5,7};
int ja[] = {0,1,1,0,2,2,1};
#endif
color = malloc (size * sizeof *color);
work = malloc (2*size * sizeof *work);
dfs(size, ia, ja, &ncolors, color, work);
fprintf(stderr, "ncolors = %d\n", ncolors);
for (j=0; j<size; ++j) {
fprintf(stderr, "%d\n", color[j]);
}
free (color);
free (work);
return 0;
}
#endif
/* Local Variables: */
/* c-basic-offset:4 */
/* End: */