Submission #540555

#	Time	Username	Problem	Language	Result	Execution time	Memory
540555		Lyestria	Keys (IOI21_keys)	C++17	100 / 100	1297 ms	149184 KiB

keys

#include <bits/stdc++.h>
using namespace std;
typedef vector<int> vi;
typedef long long ll;

const int mn = 3e5+10;

vector<int> g[mn];
unordered_map<int,vector<int>> uval[mn];
set<int> keys[mn];

void merge(int a, int b) {
	for(int k:keys[b])keys[a].insert(k);
	g[a].insert(g[a].end(), g[b].begin(), g[b].end());
	for(auto& [k,v]: uval[b]) {
		if(keys[a].count(k)){
			g[a].insert(g[a].end(), v.begin(), v.end());
		}
		else {
			auto &v2 = uval[a][k];
			v2.insert(v2.end(), v.begin(), v.end());
		}
	}
	for(int k:keys[b]){
		auto &v = uval[a][k];
		g[a].insert(g[a].end(), v.begin(), v.end());
		uval[a].erase(k);
	}
	g[b].clear();
	uval[b].clear();
	keys[b].clear();
}

struct dsu {
	vi p, sz;
	dsu(int n) : p(n), sz(n, 1) {
		for (int i = 0; i < n; i++) p[i] = i;
	}
	int f(int x) { return p[x]==x ? x : p[x] = f(p[x]); }
	void mrg(int a,int b) {
		a = f(a), b = f(b);
		if (a == b) return;
		if (sz[a] < sz[b]) swap(a, b);
		merge(a,b);
		p[b] = a;
		sz[a] += sz[b];
	}
} dsu(mn);

int bans=0x3f3f3f3f;
set<int>ans;

bool vis[mn], ins[mn];
int dfs(int x){
	vis[x]=ins[x]=1;
	while(g[x].size()){
		int y=dsu.f(g[x].back());
		g[x].pop_back();
		if(x==y)continue;
		if(ins[y]){
			ins[x]=0;
			return y;
		}
		else if(vis[y]){
			ins[x]=0;
			return -1;
		}
		int ret = dfs(y);
		if(ret == -1) {
			ins[x]=0;
			return -1;
		}
		else{
			dsu.mrg(x,y);
			if(ret == x){
				ins[x]=0;
				x = dsu.f(x);
				return dfs(x);
			}
			else {
				ins[x]=0;
				return ret;
			}
		}
	}
	if(dsu.sz[x]<bans)ans.clear();
	if(dsu.sz[x]<=bans){
		ans.insert(x);
		bans=dsu.sz[x];
	}
	ins[x]=0;
	return -1;
}


std::vector<int> find_reachable(std::vector<int> r, std::vector<int> u, std::vector<int> v, std::vector<int> c) {
	int n = r.size();
	for(int i=0;i<n;i++)keys[i].insert(r[i]);
	auto addEdge = [&](int u, int v, int c) {
		if(keys[u].count(c))g[u].push_back(v);
		else uval[u][c].push_back(v);
	};
	for(int i=0;i<u.size();i++){
		addEdge(u[i],v[i],c[i]);
		addEdge(v[i],u[i],c[i]);
	}
	for(int i=0;i<n;i++)if(!vis[i])dfs(i);
	vi ret(n);
	for(int i=0;i<n;i++)if(ans.count(dsu.f(i)))ret[i]=1;
	return ret;
}

Compilation message (stderr)

keys.cpp: In function 'std::vector<int> find_reachable(std::vector<int>, std::vector<int>, std::vector<int>, std::vector<int>)':
keys.cpp:103:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  103 |  for(int i=0;i<u.size();i++){
      |              ~^~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 11 / 11
• Subtask 3: 17 / 17
• Subtask 4: 30 / 30
• Subtask 5: 33 / 33