Submission #597502

#	Time	Username	Problem	Language	Result	Execution time	Memory
597502		PoPularPlusPlus	Let's Win the Election (JOI22_ho_t3)	C++17	100 / 100	20 ms	3332 KiB

Main

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long 
#define pb(e) push_back(e)
#define sv(a) sort(a.begin(),a.end())
#define sa(a,n) sort(a,a+n)
#define mp(a,b) make_pair(a,b)
#define vf first
#define vs second
#define ar array
#define all(x) x.begin(),x.end()
const int inf = 0x3f3f3f3f;
const int mod = 1000000007; 
const double PI=3.14159265358979323846264338327950288419716939937510582097494459230;
bool remender(ll a , ll b){return a%b;}

//freopen("problemname.in", "r", stdin);
//freopen("problemname.out", "w", stdout);

bool cmp(pair<int,int> a , pair<int,int> b){
	if(a.vs == -1)return 0;
	if(b.vs == -1)return 1;
	if(a.vs != b.vs)return a.vs < b.vs;
	return a.vf < b.vf;
}

const int N = 503;

int pre[N][N];
vector<pair<int,int>> v;
double dp[N][N];
int n , k;

double find(int x){
	if(x == 0)return pre[0][k-1];
	for(int i = 0; i <= n; i++){
		for(int j = 0; j <= n; j++)dp[i][j] = 1e9;
	}
	dp[0][0] = 0.0;
	double res = 1e9;
	for(int i = 1; i <= n; i++){
		for(int j = 0; j <= min(i,x); j++){
			if(v[i-1].vs == -1){
				goto h;
			}
			if(j == 0){
				dp[i][j] = dp[i-1][j] + (double)v[i-1].vf/(double)(x+1);
				continue;
			}
			if(j == x){
				int rem = k - i;
				res = min(res , dp[i-1][j-1] + (double)v[i-1].vs/(double)j + (rem > 0 ? (double)pre[i][rem-1]/(double)(x+1) : 0));
				dp[i][j] = dp[i-1][j] + (double)v[i-1].vf/(double)(x+1);
			}
			else {
				dp[i][j] = min(dp[i-1][j-1] + (double)v[i-1].vs/(double)j , dp[i-1][j] + (double)v[i-1].vf/(double)(x+1));
			}
		}
	}
	h:
	return res;
}

void solve(){
	cin >> n >> k;
	int cnt = 0;
	for(int i = 0; i < n; i++){
		int x , y;
		cin >> x >> y;
		v.pb(mp(x,y));
		if(y != -1)cnt++;
	}
	sort(all(v), cmp);
	vector<int> tp;
	for(int i = n - 1; i >= 0; i--){
		tp.pb(v[i].vf);
		sv(tp);
		int cur = 0 , sum = 0;
		for(int j = i; j < n; j++){
			sum += tp[cur];
			pre[i][cur] = sum;
			cur++;
		}
	}
	int l = 1 , r = min(k , cnt);
	if(cnt == 0){
		cout << pre[0][k-1] << '\n';
		return;
	}
	double ans = 1e9;
	while(l <= r){
		int mid = (l + r)/2;
		double x = find(mid) , y = find(mid - 1);
		ans = min(ans , min(x , y));
		//cout << mid << ' ' << x << ' ' << y << '\n';
		if(x > y){
			r = mid - 1;
		}
		else l = mid + 1;
	}
	cout << setprecision(10) << ans << '\n';
}

int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
	//int t;cin >> t;while(t--)
	solve();
	return 0;
}

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