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#include "cs.h"
/* depth-first-search of the graph of a matrix, starting at node j */
int cs_dfs (int j, cs *L, int top, int *xi, int *pstack, const int *Pinv)
{
int i, p, p2, done, jnew, head = 0, *Lp, *Li ;
if (!L || !xi || !pstack) return (-1) ;
Lp = L->p ; Li = L->i ;
xi [0] = j ; /* initialize the recursion stack */
while (head >= 0)
{
j = xi [head] ; /* get j from the top of the recursion stack */
jnew = Pinv ? (Pinv [j]) : j ;
if (!CS_MARKED(Lp,j))
{
CS_MARK (Lp,j) ; /* mark node j as visited */
pstack [head] = (jnew < 0) ? 0 : CS_UNFLIP (Lp [jnew]) ;
}
done = 1 ; /* node j done if no unvisited neighbors */
p2 = (jnew < 0) ? 0 : CS_UNFLIP (Lp [jnew+1]) ;
for (p = pstack [head] ; p < p2 ; p++) /* examine all neighbors of j */
{
i = Li [p] ; /* consider neighbor node i */
if (CS_MARKED (Lp,i)) continue ; /* skip visited node i */
pstack [head] = p ; /* pause depth-first search of node j */
xi [++head] = i ; /* start dfs at node i */
done = 0 ; /* node j is not done */
break ; /* break, to start dfs (i) */
}
if (done) /* depth-first search at node j is done */
{
head-- ; /* remove j from the recursion stack */
xi [--top] = j ; /* and place in the output stack */
}
}
return (top) ;
}
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