random_graph_generator.cpp

/**
*   Generates randomized graph of specified size
*
*   @author Ashwin Joisa
*   @author Praveen Gupta
*
*   Compile with [g++ random_graph_generator.cpp -std=c++11]
**/
//=============================================================================================//

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

int main(int argc, char *argv[])
{
    if (argc < 2)
    {
        cout << "Usage: " << argv[0] << " <graph_file_name>\n";
        return 0;
    }

    int n, m;
    int x, y;

    cout << "Enter number of nodes: ";
    cin >> n;
    cout << "Enter number of edges: ";
    cin >> m;

    freopen(argv[1], "w", stdout);
    cout << n << " " << m << endl;

    vector<int> *v = new vector<int>[n+1];

    // srand(time(0));
    // By defaut srand(0), so the generated graphs are same everytime
    for (int i = 0; i < m; i++) {
        do {
            x = rand() % n;
            y = rand() % n;
        } while (x == y);

        // Edge between x and y
        v[x].push_back(y);
        v[y].push_back(x);
    }

    // R
    cout << "0 ";
    int cur = 0;
    for(int i=0; i<n; i++) {
        cur += v[i].size();
        cout << cur << " ";
    }
    cout << endl;

    // C
    for(int i=0; i<n; i++)
        for(int it : v[i])
            cout << it << " ";
    cout << endl;

    delete[] v;
}

/*
-------------------------------
Example CSR format for
nodes = 5
edges = 5
-------------------------------
nodeCount edgeCount
row offset
column indices
-------------------------------
5 5
0 2 5 7 9 10 
2 3 3 2 4 0 1 1 0 1 
-------------------------------
*/