Journey to the moon Problem(graphs)

I am trying a problem on hacker rank where I am getting the TLE for some cases for following code. So i assumed that may output is coming late but when I run the code in my local compiler using the same test cases,I am getting run time error(i.e. No output at all)
I tried running the debugger but still can’t figure out what is wrong with the code.

#include <bits/stdc++.h>

using namespace std;
 * Complete the 'journeyToMoon' function below.
 * The function is expected to return an INTEGER.
 * The function accepts following parameters:
 *  1. INTEGER n
 *  2. 2D_INTEGER_ARRAY astronaut

void dfs(int n, vector<vector<int>> adj, vector<int> &visited, int src,int &count)

    visited[src] = 1;
    for (auto it : adj[src])
        if (!visited[it])
            dfs(n, adj, visited, it,count);

int journeyToMoon(int n,vector<vector<int>> adj)

    // vector<vector<int>> adj(n);
    // createAdjacencyList(n, astronaut, adj);

    vector<int> visited(n, 0);

    vector<int> components;
    int count=0;
    for (int i = 0; i < n; i++)
        if (!visited[i])
           dfs(n, adj, visited, i,count);

     int totalPairs=(n*(n-1))/2;
     int value;
     int check;
     for(int i=0;i<components.size();i++)
     return totalPairs;


int main()
    int n,p;
    vector<vector<int>> adj(n);
    for(int i=0;i<p;i++)
        int u,v;
    int result = journeyToMoon(n,adj);

    cout << result << "\n";

    // fout.close();

    return 0;

Problem Link:-

Pass adj by reference (like you’ve done with vector<int> &visited), not by value.

Do We have to pass by reference even when we are not making changes to it?
If yes,why?

You don’t have to, but it’s much more efficient than passing by value, which makes a copy of adj every single time and will almost certainly TLE.

now it is passing for all test cases.
IT was failing for 1 test case even after applying your suggestion but passed it when I changed the data type to long long int.

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