Merge pull request #418 from ishaanmehta4/patch-1

Sayansree · web-flow · commit 11a45d96aa5e · 2021-10-02T00:24:35.000+05:30
Create disjointSet.cpp
diff --git a/18. Graph/disjointSet.cpp b/18. Graph/disjointSet.cpp
@@ -0,0 +1,59 @@
+// disjoin set
+#include <bits/stdc++.h>
+using namespace std;
+
+class DisjointSet
+{
+    int *parent, *rank;
+
+public:
+    DisjointSet(int n /* no. of nodes*/)
+    {
+        parent = new int[n];
+        rank = new int[n];
+
+        for (int i = 0; i < n; i++)
+            parent[i] = i, rank[i] = 0;
+    }
+
+    int findParent(int node)
+    {
+        if (parent[node] == node)
+            return node;
+
+        return parent[node] = findParent(parent[node]);
+    }
+
+    int makeUnion(int node1, int node2)
+    {
+        int parent2 = findParent(node2);
+        int parent1 = findParent(node1);
+
+        if (rank[parent1] > rank[parent2])
+        {
+            parent[parent2] = parent1;
+        }
+        else if (rank[parent1] < rank[parent2])
+        {
+            parent[parent1] = parent2;
+        }
+        else
+        {
+            rank[parent1]++;
+            parent[parent2] = parent1;
+        }
+    }
+};
+
+int main() {
+    DisjointSet ds(5);
+    ds.makeUnion(0,4);
+    ds.makeUnion(0,1);
+    ds.makeUnion(2,3);
+    
+    cout<<ds.findParent(2)<<" "<<ds.findParent(4)<<endl;
+
+    ds.makeUnion(1,3);
+    cout<<ds.findParent(2);
+
+}
