Submission #648628

#	Time	Username	Problem	Language	Result	Execution time	Memory
648628		mychecksedad	Joker (BOI20_joker)	C++17	14 / 100	2081 ms	37352 KiB

Joker

/* Author : Mychecksdead */
#include<bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef long long int ll;
typedef long double ld;
#define MOD (1000000000+7)
#define MOD1 (998244353)
#define PI 3.1415926535
#define pb push_back
#define setp() cout << setprecision(15)
#define all(x) x.begin(), x.end()
#define oset tree<int, null_type,less_equal<int>, rb_tree_tag,tree_order_statistics_node_update>
#define debug(x) cerr << #x << " is " << x << '\n';
const int N = 1e6+100, M = 2e5+10, F = 2147483646, K = 20;

struct Dsu {
    vector<int> s, p, c;
    vector<bool> bp;
    Dsu(int n){
        s.resize(n+1, 1);
        p.resize(n+1);
        c.resize(n+1);
        bp.resize(n+1);
        for(int i = 0; i <= n; ++i) p[i] = i, c[i] = 0, bp[i] = 1;
    }
    int find(int v){
        if(p[v] != v){
            int parity = c[v];
            p[v] = find(p[v]);
            c[v] ^= parity;
        }
        return p[v];
    }
    void merge(int a, int b){
        a = find(a);
        b = find(b);
        if(a == b){
            if(c[a] == c[b])
                bp[a] = 0;
        }
        else{
            if(s[a] > s[b]){
                swap(a, b);
            }
            s[b] += s[a];
            p[a] = b;
            c[a] = c[a]^c[b]^1;
            bp[b] = bp[a] & bp[b];
        }
    }
};


int n, m, q, l, r;
bool ok;
vector<pair<int, int>> g[N], edges;
bitset<M> vis, pos;
void dfs(int v, int p, bool c){
    vis[v] = 1;
    pos[v] = c;
    for(auto k: g[v]){
        int u = k.first;
        if(l <= k.second && k.second <= r) continue;
        if(u != p){
            if(vis[u])
                ok |= pos[v] == pos[u];
            else
                dfs(u, v, !c);
        }
    }
}
void solve(){
    cin >> n >> m >> q;
    for(int i = 0; i < m; ++i){
        int u, v; cin >> u >> v;
        g[u].pb({v, i + 1});
        g[v].pb({u, i + 1});
        edges.pb({u, v});
    }
    if(n <= 2000 || q <= 2000){
        for(int i = 0; i < q; ++i){
            cin >> l >> r;
            vis = 0;
            ok = 0;
            for(int v = 1; v <= n; ++v) if(!ok && !vis[v]) dfs(v, v, 0);
            if(ok) cout << "YES\n";
            else cout << "NO\n";
        }
    }
    else{
        vector<pair<int, int>> queries[205];
        vector<int> qq(q + 1);
        for(int i = 1; i <= q; ++i){
            cin >> l >> r;
            queries[l].pb({r, i});
        }
        for(int i = 1; i <= 200; ++i){
            if(queries[i].empty()) continue;
            Dsu d(n);
            ok = 0;
            for(int j = 1; j < i; ++j){
                d.merge(edges[j - 1].first, edges[j - 1].second);
                ok |= d.bp[edges[j - 1].first] | d.bp[edges[j - 1].second];
            }
            sort(all(queries[i]), [&](const pair<int, int> &a, const pair<int, int> &b){
                return a.first > b.first;
            });
            int cur = m;
            for(auto k: queries[i]){
                while(cur > k.first){
                    d.merge(edges[cur - 1].first, edges[cur - 1].second);
                    ok |= d.bp[edges[cur - 1].first] | d.bp[edges[cur - 1].second];
                }
                if(ok) qq[k.second] = 1;
            }
        }
        for(int i = 1; i <= q; ++i) cout << (qq[i] ? "YES\n" : "NO\n");
    }
}



int main(){
    cin.tie(0); ios::sync_with_stdio(0);
    int T = 1, aa;
    // cin >> T;aa=T;
    while(T--){
        // cout << "Case #" << aa-T << ": ";
        solve();
        cout << '\n';
    }
    return 0;
 
}

Compilation message (stderr)

Joker.cpp: In function 'int main()':
Joker.cpp:127:16: warning: unused variable 'aa' [-Wunused-variable]
  127 |     int T = 1, aa;
      |                ^~

• Subtask 1: 6 / 6
• Subtask 2: 8 / 8
• Subtask 3: 0 / 25
• Subtask 4: 0 / 10
• Subtask 5: 0 / 22
• Subtask 6: 0 / 29