Submission #575295

#	Time	Username	Problem	Language	Result	Execution time	Memory
575295		talant117408	Joker (BOI20_joker)	C++17	25 / 100	334 ms	20620 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;
struct query {
    int l, r;
    int index;
    query() {
        l = r = 0;
        index = -1;
    }
};

vector <pii> graph[N], edges;
bool ans[N], odd_cycle = 0;
int color[N], used[N];
int link[N], saizu[N];
int cnt, j;
bool rev = 1;

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 (saizu[find(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 (rev == 0) {
            if (find(v) != find(to.first) || to.second <= j) continue;
        }
        else {
            if (find(v) != find(to.first) || to.second >= j) continue;
        }
        if (used[to.first] < cnt*2-1) {
            dfs(to.first, c^1);
        }
        else if (color[to.first] == color[v]) {
            odd_cycle = 1;
        }
    }
    used[v] = cnt*2;
}

void solve() {
    int n, m, q;
    cin >> n >> m >> q;
    vector <query> queries(q+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));
        graph[a].pb(mp(b, i));
        graph[b].pb(mp(a, i));
    }
    for (int i = 1; i <= q; i++) {
        cin >> queries[i].l >> queries[i].r;
        queries[i].index = i;
    }
    sort(queries.begin()+1, queries.end(), [&](query a, query b) {
        if (a.l == b.l) return a.r < b.r;
        return a.l < b.l;
    });
    
    for (int i = q; i; i--) {
        if (i == q || queries[i].l != queries[i+1].l) {
            j = m;
            odd_cycle = 0;
            for (int l = 1; l <= n; l++) {
                link[l] = l;
                saizu[l] = 1;
                used[l] = 0;
                color[l] = -1;
            }
            rev = 1;
            j = queries[i].l;
            for (int l = 1; l < queries[i].l; l++) {
                cnt++;
                unite(edges[l].first, edges[l].second);
            }
            j = m;
            rev = 0;
        }
        while (j && j > queries[i].r) {
            cnt++;
            unite(edges[j].first, edges[j].second);
            j--;
        }
        ans[queries[i].index] = odd_cycle;
    }
    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 3
1 7
1 5
1 1
1 6
1 4
1 2
1 8 

6 8 6
1 3
1 5
1 6
2 5
2 6
3 4
3 5
5 6
1 5
2 5
3 5
4 5
6 7
6 8

*/

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