Submission #937978

#	Time	Username	Problem	Language	Result	Execution time	Memory
937978		Litusiano	Let's Win the Election (JOI22_ho_t3)	C++17	16 / 100	796 ms	596 KiB

Main

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define endl "\n"
const int INF = 1e18;
mt19937 rng((unsigned int) chrono::steady_clock::now().time_since_epoch().count());

bool cmp(pair<int,int> a, pair<int,int> b){
	if(a.second == b.second) return a.first<b.first;
	return a.second < b.second;
}

void shuffle(vector<pair<int,int>>& v){
	int n = v.size();
	for(int i = 0; i<3*n; i++){
		int a = rng()%n; int b = rng()%n;
		swap(v[a],v[b]);
	}
 
}

signed main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout<<setprecision(3)<<fixed;
	int n,k1; cin>>n>>k1;

	vector<pair<int,int>> v(n);
	for(int i = 0; i<n; i++){
		cin>>v[i].first>>v[i].second;
		if(v[i].second == -1) v[i].second = INF;
	}
	if(n > 20){
		sort(v.begin(),v.end(),cmp);
		long double ans = 0;
		int cnt = 0;
		for(int i = 0; i<k1; i++){
			auto x = v[i];
			ans+=(1.0*x.first/(cnt+1));
			if(x.second == x.first) cnt++;
		}
		cout<<setprecision(10)<<fixed<<ans<<endl;
		return 0;
	}
	sort(v.begin(),v.end(),cmp);
	int q = 13000;
	long double ans = INF;
	while(q--){
		shuffle(v);
		long double dp[n+1][k1+1][k1+1];
		for(int i = 0; i<=n; i++){
			for(int j = 0; j<=k1; j++){
				for(int k = 0; k<=k1; k++) dp[i][j][k] = 1.0*INF;
			}
		}
		dp[0][0][0] = 0; // first i, j votes, k representants
		for(int i = 1; i<=n; i++){
			for(int j = 0; j<=k1; j++){
				for(int k = 0; k<=k1; k++){
					dp[i][j][k] = dp[i-1][j][k];
					if(!j) continue;
					long double act = dp[i-1][j-1][k]; // just speech for vote
					act+= 1.0*v[i-1].first/(k+1);
					dp[i][j][k] = min(dp[i][j][k],act);
					if(!k || v[i-1].second == INF) continue;
					act = dp[i-1][j-1][k-1];
					act+= 1.0*v[i-1].second / k;
					dp[i][j][k] = min(dp[i][j][k],act);
				}
			}
		}
		for(int k = 0; k<=k1; k++){
			ans = min(ans, dp[n][k1][k]);
		}
	}
	cout<<ans<<endl;
}

• Subtask 1: 5 / 5
• Subtask 2: 0 / 5
• Subtask 3: 11 / 11
• Subtask 4: 0 / 12
• Subtask 5: 0 / 33
• Subtask 6: 0 / 11
• Subtask 7: 0 / 23