Submission #395431

#	Time	Username	Problem	Language	Result	Execution time	Memory
395431		wenqi	Joker (BOI20_joker)	C++14	49 / 100	2072 ms	17220 KiB

Joker

#include <bits/stdc++.h>

using namespace std;

int N, M, Q;

int parents[600069];
int sz[600069];

int ans[600069];

#define ROOT 40

struct E {
	int i, a;
	int j, b;
};

struct R {
	int i, l, r, bl;
};

vector<E> moves;

void reset() {
	for (int i = 0; i < 2 * N; i++) {
		parents[i] = i;
		sz[i] = 1;
	}
	moves.clear();
}

int getp(int i) {
	return i == parents[i] ? i : getp(parents[i]);
}

bool join(int a, int b) {
	a = getp(a);
	b = getp(b);

	if(a == b) {
		moves.push_back({-1});
		return false;
	}

	if(sz[a] > sz[b]) {
		moves.push_back({b, parents[b], a, sz[a]});
		parents[b] = a;
		sz[a] += sz[b];
	}else{
		moves.push_back({a, parents[a], b, sz[b]});
		parents[a] = b;
		sz[b] += sz[a];
	}

	return getp(a) == getp((a + N) % (2 * N)) or getp(b) == getp((b + N) % (2 * N));
}

void reload() {
	auto p = moves.back();
	moves.pop_back();

	if(p.i == -1)
		return;

	parents[p.i] = p.a;
	sz[p.j] = p.b;
}

int A[200069];
int B[200069];

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> N >> M >> Q;
	for (int i = 1; i <= M; i++) {
		int a, b;
		cin >> a >> b;
		A[i] = --a;
		B[i] = --b;
	}
	vector<R> queries;
	for (int i = 0; i < Q; i++) {
		int l, r;
		cin >> l >> r;
		queries.push_back({i, l, r, l / ROOT});
	}
	sort(queries.begin(), queries.end(), [](R& a, R& b) {
		return a.bl < b.bl or (a.bl == b.bl and a.r > b.r);
	});
	bool made = false;
	int pbl = -1;
	int nxt = 0;
	int up = 0;
	int start = 1;
	bool doable = false;
	reset();
	for (const R& a : queries) {
		int Bs = a.bl * ROOT;

		if(a.bl != pbl) {
			doable = false;

			for(int i = 0; i < up; i++) {
				reload();
			}
			up = 0;

			for (; start < Bs; start++) {
				made |= join(A[start], B[start] + N);
				made |= join(A[start] + N, B[start]);
			}

			nxt = M;
			pbl = a.bl;
		}

		for(; nxt > a.r; nxt--) {
			doable |= join(A[nxt], B[nxt] + N);
			doable |= join(A[nxt] + N, B[nxt]);
			up += 2;
		}

		bool k = false;

		int cnt = 0;

		for (int i = Bs; i < a.l; i++) {
			if(i == 0) continue;
			k |= join(A[i], B[i] + N);
			k |= join(A[i] + N, B[i]);
			cnt += 2;
		}

		ans[a.i] = made or k or doable;

		for (int i = 0; i < cnt; i++) {
			reload();
		}
	}
	for(int i = 0; i < Q; i++) {
		cout << (ans[i] ? "YES" : "NO") << '\n';
	}
	return 0;
}

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