Strongly Connected Component

//prac problem : https://cses.fi/problemset/task/2143

//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp>
#include <functional> // for less
#include <iostream>
#define   MP             make_pair
#define   PB             push_back
#define   EB             emplace_back
#define   nn             '\n'
#define   endl           '\n'
#define   IOS            ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define   UNIQUE(vec)    vec.resize(distance(vec.begin(),unique(vec.begin(),vec.end()))) ;
#define   all(vec)       vec.begin(),vec.end()
#define   int            long long
#define   pii            pair<int,int>
#define   pdd            pair<double,double>
#define   ff             first
#define   ss             second

using namespace std ;

typedef long long LL ;

const int MOD=1e9+7,Base=998244353 ;
const int N=1e6+7 ;
const int oo=1LL*1000*1000*1000*1000*1000*1000+7LL ;
const double pie=acos(-1.0) ;
const double EPS=1e-9 ;

bitset<50005>b[50005] ;

int n, test, in[N], low[N], t, vis[N], p[N], m, roots[N] ;

vector<int> adj[N], adj_rev[N] , adj_scc[N] ;
vector<bool> used ;
vector<int> order, component , root_nodes ;

void dfs1(int v)
{
    used[v] = true;
    for (auto u : adj[v])
        if (!used[u])
            dfs1(u);
    order.push_back(v);
}

void dfs2(int v)
{
    used[v] = true;
    component.push_back(v);
    for (auto u : adj_rev[v])
        if (!used[u])
            dfs2(u);
}

void scc()
{
    used.assign(n+5, false);
    for (int i = 1; i <= n; i++)
        if (!used[i])
            dfs1(i);
    used.assign(n+5, false);
    reverse(order.begin(), order.end());
    for (auto v : order)
        if (!used[v])
        {
            dfs2 (v);
            int root = component.front();
            for (auto u : component) roots[u] = root;
            root_nodes.push_back(root);
            component.clear();
        }
    for (int v = 1; v <= n; v++)
    for (auto u : adj[v]) {
        int root_v = roots[v],
            root_u = roots[u];
        if (root_u != root_v)
            adj_scc[root_v].push_back(root_u);
    }
}

void calc(int u)
{
    if(vis[u])return ;
    b[u].set(u) , vis[u]=1 ;
    for(int v:adj_scc[u])
    {
        calc(v) , b[u]|=b[v] ;
    }
}

int32_t main()
{
    IOS

    int q, test ;

    cin>>n>>m>>q ;

    for(int i=1; i<=n; i++)
    {
        adj[i].clear() , b[i]=b[i]&b[0] , adj_rev[i].clear() ;
    }

    for(int i=1; i<=m; i++)
    {
        int u, v ;
        cin>>u>>v ;
        adj[u].PB(v) ;
        adj_rev[v].PB(u) ;
    }

    scc() ;

    for(int u:root_nodes)
    {
        calc(u) ;
    }

    while(q--)
    {
        int u, v ;
        cin>>u>>v ;
        u = roots[u] , v = roots[v] ;
        cout<<(b[u].test(v)?"YES":"NO")<<endl ;
    }

    return 0 ;
}