Merge pull request codemistic#465 from sameer-19/main

Added Kosaraju and Floyd Warshall Algorithm in CPP

Author: gantavyamalviya

CPP/graph_tree/Floyd Warshall.cpp

@@ -0,0 +1,41 @@
+// Function of floyd Warshall algorithm
+
+void floydWarshall(vector<vector<int>> &distance) // distance is the adjacency matrix of nodes 0 to n-1
+ {
+ int n=distance.size(),i,j,k;
+ 
+ for(k=0;k<n;k++)
+ {
+ for(i=0;i<n;i++)
+ {
+ for(j=0;j<n;j++)
+ {
+ if(distance[i][k]==INT_MAX || distance[k][j]==INT_MAX) continue;
+ else if(distance[i][k]+distance[k][j]<distance[i][j])
+ {
+ distance[i][j] = distance[i][k]+distance[k][j];
+ }
+ }
+ }
+ }
+ 
+ for(i=0;i<n;i++)
+ {
+ if(distance[i][i]<0) 
+ {
+ cout<<"Negative cycle present";
+ return;
+ }
+ }
+ 
+ for(i=0;i<n;i++)
+ {
+ for(j=0;j<n;j++)
+ {
+ cout<<distance[i][j]<<" ";
+ }
+ cout<<endl;
+ }
+ 
+ return;
+ }

CPP/graph_tree/Kosaraju Algorithm.cpp

@@ -0,0 +1,83 @@
+// Kosaraju Algorithm - By Sameer Aggrawal
+
+// Similar to topological sort function (dfs)
+void dfs(int node,vector<int> adj[],vector<bool> &visited,stack<int> &stk)
+{
+ visited[node] = true;
+ 
+ for(auto child: adj[node])
+ {
+ if(!visited[child])
+ {
+ dfs(child,adj,visited,stk);
+ }
+ }
+ 
+ stk.push(node);
+}
+
+void dfsRec(int node,vector<int> g[],vector<bool> &visited)
+{
+ visited[node]=true;
+ 
+ for(auto child: g[node])
+ {
+ if(!visited[child])
+ {
+ dfsRec(child,g,visited);
+ }
+ }
+ 
+ return;
+}
+
+//Function to find number of strongly connected components in the graph.
+int kosaraju(int V, vector<int> adj[])
+{
+ int i,j;
+ 
+ stack<int> stk;
+ 
+ vector<int> result;
+ vector<bool> visited(V,false);
+ 
+ for(i=0;i<V;i++)
+ {
+ if(!visited[i])
+ {
+ dfs(i,adj,visited,stk);
+ }
+ }
+ 
+ while(!stk.empty())
+ {
+ result.push_back(stk.top());
+ stk.pop();
+ }
+ 
+ vector<int> g[V];
+ 
+ for(i=0;i<V;i++)
+ {
+ for(auto x: adj[i])
+ {
+ g[x].push_back(i);
+ }
+ }
+ 
+ for(i=0;i<V;i++) visited[i]=false;
+ 
+ int cnt=0;
+ 
+ for(i=0;i<V;i++)
+ {
+ int node=result[i];
+ if(!visited[node])
+ {
+ cnt++;
+ dfsRec(node,g,visited);
+ }
+ }
+ 
+ return cnt;
+}