c_cpp HR-ComponentsInAGraph

Posted 2021-05-14

#include <bits/stdc++.h>
using namespace std;

vector<vector<int> >g; // define graph globally

void DFS(int s,  vector<bool> &visited,int &count,vector<int> &group){
    visited[s]=true;
    count++;
    group.push_back(s);
    for(int i=0;i<g[s].size();i++){
        if(!visited[g[s][i]]){
            DFS(g[s][i],visited,count,group);
        }
    }
}
vector<int> componentsInGraph(vector<vector<int>> gb) {
    //vector<vector<int> >g;
    for(int i=0;i<gb.size();i++){
        if(g.size()<=max(gb[i][0],gb[i][1])){
            g.resize(max(gb[i][0],gb[i][1])+1); // 1 indexed
        }
        g[gb[i][0]].push_back(gb[i][1]);
        g[gb[i][1]].push_back(gb[i][0]);
    }
    cout<<"Graph"<<endl;
    for(int i=1;i<g.size();i++){
        cout<<i<<"->";
        for(int j=0;j<g[i].size();j++){
            cout<<g[i][j]<<" ";
        }
        cout<<endl;
    }
    vector<bool> visited(g.size(),false);
    int minComp=INT_MAX,maxComp=INT_MIN;
    for(int i=1;i<g.size();i++){ // 1 indexed
        if(!visited[i] && g[i].size()>=1){ // IMP: check if vertex is a part of given graph
            int count=0;
            vector<int> group;
            DFS(i,visited,count,group);
            if(count>maxComp){
                maxComp=count;
            }
            if(count<minComp){
                minComp=count;
            }
            cout<<"Group"<<endl;
            for(auto i: group){
                cout<<i<<" ";
            }
            cout<<endl;
        }
    }
    cout<<minComp<<" "<<maxComp<<endl;
    vector<int> ans={minComp,maxComp};
    return ans;
}

int main(){
    //freopen("ip.txt","r",stdin);
    int e;
    cin>>e;
    vector<vector<int>> gb(e,vector<int>(2));
    for(int i=0;i<e;i++){
        cin>>gb[i][0]>>gb[i][1];
    }
    cout<<"Edges"<<endl;
    for(int i=0;i<e;i++){
        cout<<gb[i][0]<<" "<<gb[i][1];
        cout<<endl;
    }
    cout<<endl;
    vector<int> ans=componentsInGraph(gb);
    cout<<ans[0]<<" "<<ans[1]<<endl;
}