Connecting Two Barns

Only 3 testcases correct, rests are WA

I have being stuck on this problem for a long time, and I can't find out what's the bug. Can anyone please help me to find the bug?

#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
#include <cmath>
using namespace std;

void find(int node, vector<int>& g, vector<int>* adj, bool* vis){
    g.push_back(node);
    vis[node]=1;
    for(auto u : adj[node]){
        if(!vis[u]){
            find(u, g, adj, vis);
        }
    }
}

void solve(){
    int n, m; cin>>n>>m;
    vector<int> adj[n+5];
    bool vis[n+5];
    memset(vis, 0, sizeof(vis));
    for(int i=0;i<m;i++){
        int a,b; cin>>a>>b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    vector<int> F, G;
    find(1, F, adj, vis), find(n, G, adj, vis);
    sort(F.begin(), F.end());
    sort(G.begin(), G.end());

    long long cost=1e11;

    for(int i=1;i<=n;i++){
        //with the connected component of 1
        bool c=1;
        long long costOne, costN;
        if(c){
            long long c1=1e11, c2=1e11, closestIdx=upper_bound(F.begin(), F.end(), i)-F.begin();
            if(closestIdx<F.size()) c2=pow(abs(i-F[closestIdx]), 2);

            if(closestIdx-1>=0) c1=pow(abs(i-F[closestIdx-1]), 2);          
            costOne=min(c1, c2);
        }

        //with the connected component of n
        if(c){
            long long c1=1e11, c2=1e11, closestIdx=upper_bound(G.begin(), G.end(), i)-G.begin();
            if(closestIdx<G.size()) c2=pow(abs(i-G[closestIdx]), 2);
            if(closestIdx-1>=0) c1=pow(abs(i-G[closestIdx-1]), 2);
            costN=min(c1, c2);
        }

        cost=min(cost, costOne+costN);
    }
    cout<<cost<<endl;
}

int main(){
    int t; cin>>t;
    while(t--){
        solve();
    }
}