int main() {
DisjointSet<int> a, b;
assert(setFind(&a) == &a);
assert(setFind(&b) == &b);
DisjointSet<int>* c = setUnion(&a, &b);
assert(c == &a);
}
DisjointSet<T>*
setFind(DisjointSet<T>* x) {
if (x->parent == 0)
return x;
return x->parent = setFind(x->parent);
}
int disjointSets::setFind(int p)
{
//recursivly find p, return root
if(links[p] == -1)
return p;
links[p] = setFind(links[p]);
return links[p];
}
DisjointSet<T>*
setUnion(DisjointSet<T>* x, DisjointSet<T>* y) {
DisjointSet<T> *xRoot, *yRoot;
xRoot = setFind(x);
yRoot = setFind(y);
if (xRoot == yRoot)
return xRoot;
if (xRoot->rank < yRoot->rank) {
xRoot->parent = yRoot;
return yRoot;
}
else if (yRoot->rank < xRoot->rank) {
yRoot->parent = xRoot;
return xRoot;
}
else {
yRoot->parent = xRoot;
xRoot->rank++;
return xRoot;
}
}
bool validTree(int n, vector<pair<int, int>>& edges) {
vector<int> pre(n, 0);
for (int i = 0; i < n; i++) {
pre[i] = i;
}
for (int i = 0; i < edges.size(); i++) {
setUnion(pre, edges[i].first, edges[i].second);
}
int count = 0;
for (int i = 0; i < n; i++) {
if (setFind(pre, i) == i) count++;
}
return count == 1 && edges.size() == n - 1;
}
int
setContains(SET set,void *elt)
{
return setFind(set,elt) != NULL;
}
void setUnion(vector<int>& pre, int x, int y) {
x = setFind(pre, x);
y = setFind(pre, y);
pre[x] = y;
}
int setFind(vector<int>& pre, int x) {
if (pre[x] != x) {
pre[x] = setFind(pre, pre[x]);
}
return pre[x];
}
