Create quick_union.cc

trees/quick_union.cc

@@ -0,0 +1,22 @@
+class quick_union {
+private:
+    vector<size_t> c;
+public:
+    quick_union(size_t n) : c(n) {
+        iota(c.begin(), c.end(), 0);
+    }
+    
+    size_t query(size_t i) {
+        if (c[i] != i) c[i] = query(c[i]);
+        return c[i];
+    }
+    
+    void merge(size_t i, size_t j) {
+        c[query(i)] = query(j);
+    }
+
+    bool connected(size_t i, size_t j) {
+        return query(i) == query(j);
+    }
+};
+