code.cpp

// g++ -std=c++11 code.cpp -o code && ./code
// g++ -std=c++11 code.cpp && ./a.out

/*
todo:Graph Representation:
-----------------------

todo:Topic: Adjency Matrix
-----------------------
Adjency list : using vector in c++ \ linked list

A---B
    / \
    C---D

if
A=>0
B=>1
C=>2
D=>3

0---1
    / \
    2---3

list:

0-> 1
1 -> 0,2,3
2 -> 1,3
3 -> 1,2

no. of nodes =4

--output--



*/

#include <iostream>
#include <vector>
using namespace std;

int main()
{
    const int nodes = 4;  // must be const
    // int matrix[nodes][nodes] = {}; // zero-initialized
    vector<int>adj_list[nodes];

    adj_list[0]={1};
    adj_list[1]={0,2,3};
    adj_list[2]={1,3};
    adj_list[3]={1,2};

    for(int i =0; i<nodes; i++){
        cout<<"i->";
        for (int j=0; j< adj_list[i].size(); j++){
            cout<<adj_list[i][j]<<" ";
        }
        cout<<endl;
    }
   

    return 0;
}