Union find template

Author: ShengkaiLee

.DS_Store

@@ -0,0 +1,29 @@
+class UnionFind {
+ private:
+ vector<int> parent, rank;
+ int cnt;
+ public:
+ UnionFind(int cnt) : cnt(cnt) {
+ parent = vector<int>(cnt);
+ rank = vector<int>(cnt, 0);
+ for (int i = 0; i < cnt; ++i) parent[i] = i;
+ }
+ int find(int p) {
+ if (parent[p] == p) return p;
+ return parent[p] = find(parent[p]);
+ }
+ bool connected(int p, int q) { 
+ return find(p) == find(q); 
+ }
+ voparent connect(int p, int q) {
+ int i = find(p), j = find(q);
+ if (i == j) return;
+ if (rank[i] < rank[j]) {
+ parent[i] = j; 
+ } else {
+ parent[j] = i;
+ if (rank[i] == rank[j]) rank[j]++;
+ }
+ --cnt;
+ }
+};