quick union optimized with rank # O(nlogn) finished

Author: Zu3zz

union-find/04-quick-union-optimized-based-on-rank/main.cpp

@@ -0,0 +1,52 @@
+#include <iostream>
+#include <cassert>
+
+using namespace std;
+
+namespace UF4{
+  class UnionFind{
+  private:
+    int* parent;
+    int* rank; // size[i]表示以i为根的集合所表示的层数
+    int count;
+  public:
+    UnionFind(int count){
+      parent = new int[count];
+      rank = new int[count];
+      this->count = count;
+      for(int i = 0; i < count; i++)
+      {
+        parent[i] = i;
+        rank[i] = 1;
+      }
+    }
+    ~UnionFind(){
+      delete [] parent;
+      delete [] rank;
+    }
+    int find(int q){
+      assert(q >= 0 && q < count);
+      while(q != parent[q]){
+        q = parent[q];
+      }
+      return q;
+    }
+    bool isConnected(int p, int q){
+      return find(q) == find(q);
+    }
+    void unionElements(int p, int q){
+      int pRoot = find(p);
+      int qRoot = find(q);
+      if(qRoot == pRoot)
+        return;
+      if(rank[pRoot] < rank[qRoot]){
+        parent[pRoot] = qRoot;
+      } else if (rank[qRoot] < rank[pRoot]){
+        parent[qRoot] = pRoot;
+      } else { // rank[pRoot] = rank[qRoot]
+        parent[pRoot] = qRoot;
+        rank[qRoot] +=1;
+      }
+    }
+  };
+}