Submission #858780

#	Time	Username	Problem	Language	Result	Execution time	Memory
858780		maks007	Joker (BOI20_joker)	C++14	0 / 100	369 ms	7032 KiB

Joker

#include "bits/stdc++.h"

using namespace std;

vector <vector <int> > g;
vector <int> used, rk, p;
int f;

int get(int v) {
	if(v == p[v]) return v;
	return p[v] = get(p[v]);
}

void unite(int a, int b) {
	a = get(a);
	b = get(b);
	if(a == b) return;
	rk[a] += rk[b];
	p[b] = a;
}

void dfs(int v, int dist = 1, int p = -1) {
	used[v] = dist;
	for(auto i : g[v]) {
		if(p == i) continue;
		if(used[i]==-1) dfs(i, (dist+1)%2, v);
		else {
			if(used[i] == used[v]) f = 1;
		}
	}
}
void renname(int v, int p) {
	used[v] = 1-used[v];
	for(auto i : g[v]) {
		if(i == p) continue;
		renname(i, v);
	}
}
void d(int v, int u) {
	if(used[v] == used[u] && get(u) == get(v)) f = 1;
	else {
		for(auto &j:used)j=-1;
		dfs(v);
	}
}

signed main () {
	int n, m, q;
	cin >> n >> m >> q;
	g.resize(n);
	used.resize(n, -1);
	rk.resize(n, 1);
	p.resize(n);
	for(int i = 0; i < n; i ++) p[i] = i;
	vector <pair <int,int>> edge;
	for(int i = 0; i < m; i ++) {
		int u, v;
		cin >> u >> v;
		edge.push_back({u-1, v-1});
	}
	vector <int> suff(m + 1);
	suff[m] = 0;
	for(int i = m - 1; i >= 0; i --) {
		if(suff[i+1] == 1) {
			suff[i] = suff[i+1]; 
			continue;
		}
		g[edge[i].first].push_back(edge[i].second);
		g[edge[i].second].push_back(edge[i].first);
		unite(edge[i].first, edge[i].second);
		f = 0;
		d(edge[i].first, edge[i].second);
		if(f) suff[i] = 1;
		else suff[i] = 0;
	}
	while(q --) {
		int l, r;
		cin >> l >> r;
		l --, r --;
		if(l == 0) {
			if(suff[r+1] == 1) cout << "YES\n";
			else cout << "NO\n";
			continue;
		}
		for(auto &i : g) i.clear();
		for(auto &i : used) i = -1;
		for(int i = 0; i < l; i ++) {
			g[edge[i].first].push_back(edge[i].second);
			g[edge[i].second].push_back(edge[i].first);
		}
		for(int i = r+1; i < m; i ++) {
			g[edge[i].first].push_back(edge[i].second);
			g[edge[i].second].push_back(edge[i].first);
		}
		for(int i = 0; i < n; i ++) {
			if(used[i]==-1) {
				f = 0;
				dfs(i);
				if(f) {
					cout << "YES\n";
					goto end;
				}
			}
		}
		cout << "NO\n";
		end:;
	}
	return 0;
}

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