Submission #1066082

#	Time	Username	Problem	Language	Result	Execution time	Memory
1066082		pcc	Longest Trip (IOI23_longesttrip)	C++17	70 / 100	29 ms	1120 KiB

longesttrip

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

#define vi vector<int>

const int mxn = 300;

vector<int> perm;
 
int ask(vector<int> a,vector<int> b){
	for(auto &i:a)i = perm[i];
	for(auto &i:b)i = perm[i];
	return are_connected(a,b);
}

int dp[mxn][mxn];
bitset<mxn> vis;
int N;

int ask(int a,int b){
	if(dp[a][b] != -1)return dp[a][b];
	//cerr<<"ASK: "<<a<<','<<b<<endl;
	return dp[a][b] = dp[b][a] = ask(vector<int>({a}),vector<int>({b}));
}
int ask(deque<int> a,int b){
	vi v;
	for(auto &i:a)v.push_back(i);
	return ask(v,vi({b}));
}

void dfs(int now){
	vis[now] = true;
	for(int i = 0;i<N;i++){
		if(i != now&&!vis[i]&&ask(now,i))dfs(i);
	}
	return;
}


bitset<mxn> done;
vector<int> get_max_cc(){
	//cerr<<"GETTING MAX CC: "<<endl;
	done.reset();
	int ans = 0,tar = -1;
	for(int i = 0;i<N;i++){
		if(!done[i]){
			vis.reset();
			dfs(i);
			if(ans<vis.count()){
				ans = vis.count();
				tar = i;
			}
			done = done|vis;
		}
		//cerr<<i<<":";for(int j = 0;j<N;j++)cerr<<done[j]<<' ';cerr<<endl;
	}
	assert(tar != -1);
	vis.reset();
	dfs(tar);
	vector<int> re;
	for(int i = 0;i<N;i++)if(vis[i])re.push_back(i);
	for(auto &i:re)i = perm[i];
	return re;
}

std::vector<int> longest_trip(int NN, int D){
	N = NN;
	perm = vector<int>(N);iota(perm.begin(),perm.end(),0);
	mt19937 seed(time(0));
	shuffle(perm.begin(),perm.end(),seed);
	memset(dp,-1,sizeof(dp));
	vis.reset();
	for(int i = 0;i<N;i++){
		dp[i][i] = 1;
	}
	/*
	dfs(1);
	if(vis.count() != N){
		return get_max_cc();
	}
	*/
	cerr<<"------------------------"<<endl;
	deque<int> dq[2];
	set<int> st;
	for(int i = 0;i<N;i++)st.insert(i);
	if(ask(0,1))dq[0] = {0,1};
	else if(ask(1,2))dq[0] = {1,2};
	else dq[0] = {0,2};
	for(auto &i:dq[0])st.erase(i);
 
	while(st.size()){
		if(dq[0].size()<dq[1].size())dq[0].swap(dq[1]);
		//cerr<<*st.begin()<<endl;
		auto now = *st.begin();
		st.erase(now);
		if(ask(now,dq[0].back())){
			dq[0].push_back(now);
			dq[0].swap(dq[1]);
		}
		else{
			dq[1].push_back(now);
		}
		if(dq[0].empty()||dq[1].empty())continue;
		int s = dq[0].front(),t = dq[0].back();
		if(!ask(s,t)){
			if(ask(s,now)){
				while(!dq[1].empty()){
					dq[0].push_front(dq[1].back());
					dq[1].pop_back();
				}
			}
			else{
				while(!dq[1].empty()){
					dq[0].push_back(dq[1].back());
					dq[1].pop_back();
				}
			}
		}
		else{
			auto c = dq[0];
			if(!ask(c,now))continue;
			while(c.size()>1){
				int mid = c.size()/2;
				deque<int> tmp;
				for(int i = 0;i<mid;i++)tmp.push_back(c[i]);
				if(ask(tmp,now))while(c.size()>mid)c.pop_back();
				else for(int i = 0;i<mid;i++)c.pop_front();
			}
			int tar = -1;
			//cerr<<now<<"::";for(auto &i:c)cerr<<i<<',';cerr<<endl;
			if(c.size()==1)tar = c[0];
			if(tar == -1)continue;
			while(dq[0][0] != tar){
				dq[0].push_back(dq[0][0]);
				dq[0].pop_front();
			}
			while(!dq[1].empty()){
				dq[0].push_front(dq[1].back());
				dq[1].pop_back();
			}
		}
	}
 
	if(dq[0].size()<dq[1].size())dq[0].swap(dq[1]);
	/*
	cerr<<"DQ: "<<endl;
	for(auto &i:dq[0])cerr<<i<<' ';cerr<<endl;
	for(auto &i:dq[1])cerr<<i<<' ';cerr<<endl;
	cerr<<endl;
	*/
	vector<int> ans;
	for(auto &i:dq[0])ans.push_back(i);
	for(auto &i:ans)i = perm[i];
	return ans;
}

Compilation message (stderr)

longesttrip.cpp: In function 'std::vector<int> get_max_cc()':
longesttrip.cpp:50:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::size_t' {aka 'long unsigned int'} [-Wsign-compare]
   50 |    if(ans<vis.count()){
      |       ~~~^~~~~~~~~~~~
longesttrip.cpp: In function 'std::vector<int> longest_trip(int, int)':
longesttrip.cpp:127:35: warning: comparison of integer expressions of different signedness: 'std::deque<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  127 |     if(ask(tmp,now))while(c.size()>mid)c.pop_back();
      |                           ~~~~~~~~^~~~

• Subtask 0: 0 / 0
• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 25 / 25
• Subtask 4: 30 / 60