Submission #575260

#	Time	Username	Problem	Language	Result	Execution time	Memory
575260		talant117408	Joker (BOI20_joker)	C++17	0 / 100	635 ms	32856 KiB

Joker

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
 
#define pb                  push_back
#define mp                  make_pair
#define all(v)              (v).begin(),(v).end()
#define rall(v)             (v).rbegin(),(v).rend()
#define lb                  lower_bound
#define ub                  upper_bound
#define sz(v)               int((v).size())
#define do_not_disturb      ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl                '\n'

const int N = 2e5+7;
vector <int> graph[N];
vector <pii> edges;
struct query {
    int l, r;
    int index;
    query() {
        l = r = 0;
        index = -1;
    }
};
bool ans[N];
int color[N];
int used[N];
bool odd_cycle = 0;
int link[N], saizu[N];
int cnt, j;
map <pii, int> edges_index;

int find(int n) {
    if (link[n] == n) return n;
    return link[n] = find(link[n]);
}

void dfs(int v, int c);

void unite(int a, int b) {
    if (find(a) == find(b)) {
        if (color[a] == color[b]) odd_cycle = 1;
        return;
    }
    if (saizu[find(a)] < saizu[find(b)]) swap(a, b);
    saizu[find(a)] += saizu[find(b)];
    link[find(b)] = find(a);
    if (color[a] == -1) {
        dfs(a, 0);
    }
    else {
        used[a] = cnt*2;
        dfs(b, color[a]^1);
    }
}

void dfs(int v, int c) {
    used[v] = cnt*2-1;
    color[v] = c;
    for (auto to : graph[v]) {
        if (edges_index[mp(min(v, to), max(v, to))] < j) continue;
        if (used[to] == cnt*2 || used[to] == cnt*2-1) {
            if (used[to] == cnt*2-1 && color[v] == color[to]) {
                odd_cycle = 1;
            }
            continue;
        }
        dfs(to, c^1);
    }
    used[v] = cnt*2;
}

void solve() {
    int n, m, q;
    cin >> n >> m >> q;
    vector <query> queries(q+1);
    for (int i = 1; i <= n; i++) {
        color[i] = -1;
        link[i] = i;
        saizu[i] = 1;
    }
    edges.pb(mp(0, 0));
    for (int i = 1; i <= m; i++) {
        int a, b;
        cin >> a >> b;
        if (a > b) swap(a, b);
        edges.pb(mp(a, b));
        edges_index[mp(a, b)] = i;
        graph[a].pb(b);
        graph[b].pb(a);
    }
    for (int i = 1; i <= q; i++) {
        cin >> queries[i].l >> queries[i].r;
        queries[i].index = i;
    }
    sort(all(queries), [&](query a, query b) {
        if (a.l == b.l) return a.r < b.r;
        return a.l < b.l;
    });
    
    j = m;
    while (j > queries.back().r) {
        cnt++;
        unite(edges[j].first, edges[j].second);
        j--;
    }
    for (int i = q; i; i--) {
        ans[queries[i].index] = odd_cycle;
        if (i == q || queries[i].r != queries[i+1].r) {
            cnt++;
            unite(edges[j].first, edges[j].second);
            j--;
        }
        while (j > 0 && i > 1 && j > queries[i-1].r) {
            cnt++;
            unite(edges[j].first, edges[j].second);
            j--;
        }
    }
    for (int i = 1; i <= q; i++) {
        cout << (ans[i] ? "YES" : "NO") << endl;
    }
}

int main() {
    //~ do_not_disturb
    
    int t = 1;
    //~ cin >> t;
    while (t--) {
        solve();
    }
    
    return 0;
}
/*
6 8 8
1 3
1 5
1 6
2 5
2 6
3 4
3 5
5 6
1 8 
1 7
1 6
1 5
1 4
1 3
1 2
1 1
*/

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