Travelling is Fun - Union Find

#include <bits/stdc++.h>
#define maxm 200001
#define ll long long

using namespace std;

ll n, g, q;
vector<ll> origin(maxm), dest(maxm), root(maxm), child(maxm);

ll findroot(ll x){
    while(x != root[x])
        x = root[x];
    return x;
}

void _union(ll x, ll y){
    ll rootx = findroot(x);
    ll rooty = findroot(y);
    if(rootx == rooty)
        return;
    if(child[rootx] < child[rooty]){
        root[rootx] = root[rooty];
        child[rooty] += child[rootx];
    }
    else{
        root[rooty] = root[rootx];
        child[rootx] += child[rooty];
    }
}

void solve(){
    if(!g){
        for(ll i=0; i<q; ++i)
            cout<<1<<endl;
        return;
    }
    for(ll i=1; i<=n; ++i){
        root[i] = i;
        child[i] = 1;
    }
    for(ll i=g+1; i<=n; ++i){
        if(root[i] != i)
            continue;
        for(ll j=2*i; j<=n; j+=i)
            _union(i, j);
    }
    for(ll i=0; i<q; ++i)
        cout<<(findroot(origin[i]) == findroot(dest[i]))<<endl;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin>>n>>g>>q;
    for(ll i=0; i<q; ++i)
        cin>>origin[i];
    cin>>q;
    for(ll i=0; i<q; ++i)
        cin>>dest[i];
    solve();
    return 0;
}