diff --git a/graph/connected_components.cpp b/graph/connected_components.cpp
index a23a54b42..f970f17a2 100644
--- a/graph/connected_components.cpp
+++ b/graph/connected_components.cpp
@@ -4,20 +4,20 @@
 using std::vector;
 
 class graph {
-  private:
-    vector<vector<int>> adj;
-    int connected_components;
-    void depth_first_search();
-    void explore(int, vector<bool>&);
-  public:
-    graph(int n): adj(n, vector<int>()) {
-      connected_components = 0;
-   }
-   void addEdge(int, int);
-   int getConnectedComponents() {
-      depth_first_search();
-      return connected_components;
-    }
+private:
+  vector<vector<int>> adj;
+  int connected_components;
+  void depth_first_search();
+  void explore(int, vector<bool>&);
+public:
+  explicit graph(int n): adj(n, vector<int>()) {
+    connected_components = 0;
+  }
+  void addEdge(int, int);
+  int getConnectedComponents() {
+    depth_first_search();
+    return connected_components;
+  }
 };
 
 void graph::addEdge(int u, int v) {