Submission #1039521

#	Time	Username	Problem	Language	Result	Execution time	Memory
1039521		pcc	Parking (CEOI22_parking)	C++17	10 / 100	1881 ms	23744 KiB

Main

#include <bits/stdc++.h>
using namespace std;

#define pii pair<int,int>
#define fs first
#define sc second

const int mxn = 2e5+10;
int arr[mxn][2];
vector<int> pos[mxn];
set<int> spare;
int N,M;
priority_queue<pii,vector<pii>,greater<pii>> pq;
bitset<mxn> done;
vector<pii> ans;

void add(int col){
	if(!col)return;
	int p1 = pos[col][0],p2 = pos[col][1];
	if(p1&1)swap(p1,p2);
	if((p1&1)&&(p2&1))pq.push(pii(3,col));
	else if(!(p1&1)&&(p2&1)){
		if((arr[p1>>1][1]))pq.push(pii(2,col));
		else pq.push(pii(0,col));
	}
	else if(!(p1&1)&&!(p2&1)){
		if(arr[p1>>1][1]||arr[p2>>1][1])pq.push(pii(1,col));
		else pq.push(pii(0,col));
	}
	else assert(false);
}

void mv(int a,int b){
	cerr<<"MV: "<<a<<' '<<b<<endl;
	ans.push_back(pii(a,b));
	assert(spare.find(a) == spare.end());
	assert(arr[a][0]&&!arr[b][1]);
	int pa = (a<<1)|(arr[a][1]?1:0);
	int pb = (b<<1)|(!arr[b][0]?0:1);
	int col = arr[pa>>1][pa&1];
	swap(arr[pb>>1][pb&1],arr[pa>>1][pa&1]);
	pos[col].erase(find(pos[col].begin(),pos[col].end(),pa));
	pos[col].push_back(pb);
	assert(pos[col].size() == 2);
	if(!arr[pa>>1][0])spare.insert(pa>>1);
	add(arr[pa>>1][0]);
	add(col);
	add(arr[pb>>1][0]);
	return;
}

int main(){
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin>>N>>M;
	for(int i = 1;i<=M;i++){
		for(int j = 0;j<2;j++){
			cin>>arr[i][j];
			if(arr[i][j])pos[arr[i][j]].push_back((i<<1)|j);
		}
		if(!arr[i][0])spare.insert(i);
	}
	for(int i = 1;i<=N;i++){
		assert(pos[i].size() == 2);
		if((pos[i][0]^pos[i][1]) == 1)done[i] = true;
		else{
			add(i);
		}
	}
	if(N == M){
		if(done.count() != N)cout<<"-1\n";
		else cout<<"0\n";
		return 0;
	}
	while(!pq.empty()){
		auto [tp,col] = pq.top();pq.pop();
		if(done[col])continue;
		int p1 = pos[col][0],p2 = pos[col][1];
		if(p1&1)swap(p1,p2);
		cerr<<tp<<' '<<col<<':'<<p1<<' '<<p2<<endl;
		if(tp == 3||tp == 2){
			if(spare.empty()){
				cout<<"-1\n";
				return 0;
			}
			auto emp = *spare.begin();
			spare.erase(emp);
			mv(p1>>1,emp);
		}
		else if(tp == 1){
			if(arr[p1>>1][1])swap(p1,p2);
			if(spare.empty()){
				cout<<"-1\n";
				return 0;
			}
			auto emp = *spare.begin();
			spare.erase(emp);
			mv(p2>>1,emp);
		}
		else if(tp == 0){
			mv(p2>>1,p1>>1);
			done[col] = true;
		}
	}
	cerr<<"ANS: "<<endl;
	for(int i = 1;i<=M;i++)cerr<<arr[i][0]<<' '<<arr[i][1]<<endl;
	cerr<<endl<<endl;
	cout<<ans.size()<<'\n';
	for(auto [a,b]:ans)cout<<a<<' '<<b<<'\n';
	return 0;
}

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:70:19: warning: comparison of integer expressions of different signedness: 'std::size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   70 |   if(done.count() != N)cout<<"-1\n";
      |      ~~~~~~~~~~~~~^~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 25
• Subtask 4: 0 / 15
• Subtask 5: 0 / 25
• Subtask 6: 0 / 15