/* find_longest_path:
* Find and return longest path in tree.
*/
static nodelist_t*
find_longest_path(Agraph_t* tree)
{
Agnode_t* n;
Agedge_t* e;
Agnode_t* common = 0;
nodelist_t* path;
nodelist_t* endPath;
int maxlength = 0;
int length;
if (agnnodes(tree) == 1) {
path = mkNodelist();
n = agfstnode(tree);
appendNodelist(path, NULL, n);
SET_ONPATH(n);
return path;
}
for(n = agfstnode(tree); n; n = agnxtnode(tree, n)) {
int count = 0;
for(e = agfstedge(tree, n); e; e = agnxtedge(tree, e, n)) {
count++;
}
if(count == 1)
measure_distance(n, n, 0, NULL);
}
/* find the branch node rooted at the longest path */
for(n = agfstnode(tree); n; n = agnxtnode(tree, n)) {
length = DISTONE(n) + DISTTWO(n);
if(length > maxlength) {
common = n;
maxlength = length;
}
}
path = mkNodelist();
for (n = LEAFONE(common); n != common; n = TPARENT(n)) {
appendNodelist(path, NULL, n);
SET_ONPATH(n);
}
appendNodelist(path, NULL, common);
SET_ONPATH(common);
if (DISTTWO(common)) { /* 2nd path might be empty */
endPath = mkNodelist();
for (n = LEAFTWO(common); n != common; n = TPARENT(n)) {
appendNodelist(endPath, NULL, n);
SET_ONPATH(n);
}
reverseAppend(path, endPath);
}
return path;
}
/* place_node:
* Add n to list. By construction, n is not in list at start.
*/
static void place_node(Agraph_t * g, Agnode_t * n, nodelist_t * list)
{
Agedge_t *e;
int placed = 0;
nodelist_t *neighbors = mkNodelist();
nodelistitem_t *one, *two;
for (e = agfstout(g, n); e; e = agnxtout(g, e)) {
appendNodelist(neighbors, NULL, e->head);
SET_NEIGHBOR(e->head);
}
for (e = agfstin(g, n); e; e = agnxtin(g, e)) {
appendNodelist(neighbors, NULL, e->tail);
SET_NEIGHBOR(e->tail);
}
/* Look for 2 neighbors consecutive on list */
if (sizeNodelist(neighbors) >= 2) {
for (one = list->first; one; one = one->next) {
if (one == list->last)
two = list->first;
else
two = one->next;
if (NEIGHBOR(one->curr) && NEIGHBOR(two->curr)) {
appendNodelist(list, one, n);
placed = 1;
break;
}
}
}
/* Find any neighbor on list */
if (!placed && sizeNodelist(neighbors) > 0) {
for (one = list->first; one; one = one->next) {
if (NEIGHBOR(one->curr)) {
appendNodelist(list, one, n);
placed = 1;
break;
}
}
}
if (!placed)
appendNodelist(list, NULL, n);
for (one = neighbors->first; one; one = one->next)
UNSET_NEIGHBOR(one->curr);
freeNodelist(neighbors);
}
