Strongly Connected Component (SCC)

Strongly Connected Components pseudocode:

SCC(G)

1. call DFS(G) to compute finishing times f [u] for all u
2. compute G^T
3. call DFS(G^T), but in the main loop, consider vertices in order of decreasing f [u] (as computed in first DFS)
4. output the vertices in each tree of the depth-first forest formed in second DFS as a separate SCC

Here is a simple implementation:

#include<cstdio>
#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
#define sz 100
vector<int> graph[sz],Gt[sz]; //graph[] store the graph and Gt[] store transpose graph
vector<int> topo;
int disc[sz],fin[sz],color[sz];
int time=0;

void dfs_visit(int node,int flag)
{
    int i,j,k,temp;

    color[node]=1;
    if(flag==0) //for the general graph, first dfs call
    {
        disc[node]= ++time;

        for(i=0;i<graph[node].size();i++)
        {
            temp=graph[node][i];
            if(color[temp]==0)
                dfs_visit(temp,flag);
        }
        fin[node]= ++time;
        topo.push_back(node);
    }
    else //for the transpose graph, second dfs call
    {
        printf("%d ",node);
        for(i=0;i<Gt[node].size();i++)
        {
            temp=Gt[node][i];
            if(color[temp]==0)
                dfs_visit(temp,flag);
        }
    }

    color[node]=2;
}


void dfs(int node,int flag)
{
    int i,j;

    if(flag==0) //for the general graph, first dfs call
    {
        for(i=0;i<node;i++)
        {
            if(color[i]==0)
                dfs_visit(i,flag);
        }
    }
    else //for the transpose graph, second dfs call
    {
        for(i=0;i<topo.size();i++)
        {
            if(color[topo[i]]==0)
            {
                dfs_visit(topo[i],flag);
                puts("");
            }

        }
    }
}

int main()
{
    int i,j,k,num,t,node,edge,a,b;

    scanf("%d%d",&node,&edge);

    for(i=0;i<edge;i++)
    {
        scanf("%d%d",&a,&b);
        graph[a].push_back(b);  //directed graph
        Gt[b].push_back(a);     //transpose graph
    }

 //dfs in graph
    for(i=0;i<node;i++) color[i]=0;
    
 dfs(node,0);
 
 //finding topological sort
    reverse(topo.begin(),topo.end());
    
    //dfs in transpose graph
    for(i=0;i<node;i++) color[i]=0;
 
    dfs(node,1); //connected components will be printed in this call

    return 0;
}