Added docs

graph/connected_components.cpp

@@ -1,29 +1,86 @@
+/**
+ *
+ * \file
+ * \brief [Connected Components
+ * (Connected Components)](https://en.wikipedia.org/wiki/Component_(graph_theory))
+ *
+ * \author [Ayaan Khan](http://github.com/ayaankhan98)
+ *
+ * \details
+ * A graph is a collection of nodes also called vertices and these vertices
+ * are connected by edges. A connected component in a graph refers to a set of
+ * vertices which are reachable form one another.
+ *
+ * Example - Here is graph with 3 connected components
+ *
+ *      3   9           6               8
+ *     / \ /           / \             / \
+ *    2---4           2   7           3   7
+ *
+ *    first          second           third
+ *    component      component        component
+ *
+ */
+
+#include <algorithm>
 #include <iostream>
 #include <vector>
 
 using std::vector;
 
+/**
+ * Class for representing graph as a adjacency list.
+ */
 class graph {
  private:
+   /** \brief adj stores adjacency list representation of graph */
     vector<vector<int>> adj;
+
+    /** \brief keep track of connected components */
     int connected_components;
+
+    /** \brief Utility function to perform depth first search on graph */
     void depth_first_search();
+
+    /** \brief Utility function that explores given vertex in graph */
     void explore(int, vector<bool> &);
 
  public:
+    /** 
+     * \brief Constructor that intiliazes the graph on creation and set
+     * the connected components to 0
+     */
     explicit graph(int n) : adj(n, vector<int>()) { connected_components = 0; }
+    
+    /** \brief Function to add a edge between two nodes or vertices of graph */
     void addEdge(int, int);
+
+    /** 
+     * \brief Function the calculates the connected compoents in the graph
+     * by performing the depth first search on graph
+     *
+     * @return connected_components total connected components in graph
+     */
     int getConnectedComponents() {
         depth_first_search();
         return connected_components;
     }
 };
 
+/**
+ * \brief Function that add edge between two nodes or vertices of graph
+ *
+ * @param u any node or vertex of graph
+ * @param v any node or vertex of graph
+ */
 void graph::addEdge(int u, int v) {
     adj[u - 1].push_back(v - 1);
     adj[v - 1].push_back(u - 1);
 }
 
+/**
+ * \brief Function that perfoms depth first search algorithm on graph
+ */
 void graph::depth_first_search() {
     int n = adj.size();
     vector<bool> visited(n, false);
@@ -35,7 +92,13 @@ void graph::depth_first_search() {
         }
     }
 }
-
+/**
+ * \brief Utility function for depth first seach algorithm
+ * this function explores the vertex which is passed into.
+ *
+ * @param u vertex or node to be explored
+ * @param visited already visited vertex
+ */
 void graph::explore(int u, vector<bool> &visited) {
     visited[u] = true;
     for (auto v : adj[u]) {
@@ -45,10 +108,16 @@ void graph::explore(int u, vector<bool> &visited) {
     }
 }
 
+/** Main function */
 int main() {
+  /// creating a graph with 4 vertex 
     graph g(4);
+
+  /// Adding edges between vertices
     g.addEdge(1, 2);
     g.addEdge(3, 2);
+
+  /// printing the connected components
     std::cout << g.getConnectedComponents();
     return 0;
 }