Merge pull request #761 from ayaankhan98/master

Connected Components using DFS

graph/connected_components.cpp

@@ -0,0 +1,55 @@
+#include <iostream>
+#include <vector>
+
+using std::vector;
+
+class graph {
+ 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) {
+  adj[u-1].push_back(v-1);
+  adj[v-1].push_back(u-1);
+}
+
+void graph::depth_first_search() {
+  int n = adj.size();
+  vector<bool> visited(n, false);
+
+  for (int i = 0 ; i < n ; i++) {
+    if (!visited[i]) {
+      explore(i, visited);
+      connected_components++;
+    }
+  }
+}
+
+void graph::explore(int u, vector<bool> &visited) {
+  visited[u] = true;
+  for (auto v : adj[u]) {
+    if (!visited[v]) {
+      explore(v, visited);
+    }
+  }
+}
+
+int main() {
+  graph g(4);
+  g.addEdge(1, 2);
+  g.addEdge(3, 2);
+  std::cout << g.getConnectedComponents();
+  return 0;
+}