2 test cases not passing

#1

#include <bits/stdc++.h>
#include
#include<stdio.h>
#include
#include<math.h>
#include
#include
#include
#include
#include

// #include < unordered_map >
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;

#define ll long long
#define pb push_back
#define P pair<ll,ll>
#define F first
#define S second

const ll N = 100005;

struct Graph{

ll size;
vector<ll> *adjlist;

Graph(ll n){
    size=n;
    adjlist=new vector<ll>[size];
}

void addedge(ll a,ll b){
    adjlist[a].pb(b);
    adjlist[b].pb(a);
}

ll dfs_helper(bool *visited,ll node){
    bool flag=false;
    for(auto x : adjlist[node]){
        if(!visited[x]){
            flag=true;
        }
    }
    if(flag==false) return 1;
   ll val=1;
    visited[node]=true;
    for(auto neighbour : adjlist[node]){

        if(!visited[neighbour]){
           val+=dfs_helper(visited,neighbour);
        }
    }
    // cout<<val<<endl;
    return val;     
}
ll dfs(){
    bool *visited=new bool[size];
    memset(visited,false,sizeof(visited));
    ll ans=(size)*(size-1)/2;

    for(ll i=0;i<size;i++){
       ll node = i;
       if(!visited[node]){
           ll temp= dfs_helper(visited,node);
           ans-=(temp)*(temp-1)/2;
       }
    }
    return ans;
}

};

int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);

ll n,e;
cin>>n>>e;

if(n==2||n==1){
	cout<<0<<endl;
	return 0;
}

struct Graph g(n);

for(ll i=0;i<e;i++){
    ll e1,e2;
    cin>>e1>>e2;
    g.addedge(e1,e2);
}

cout<<g.dfs();

}
This is my code for this question. Please tell why 2 test cases are not working

#2

Please send your code link.
Meanwhile you can refer this -:

#3

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