Submission #1194472

#	Time	Username	Problem	Language	Result	Execution time	Memory
1194472		biank	Let's Win the Election (JOI22_ho_t3)	C++20	23 / 100	2594 ms	456 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define forn(i,n) for(int i=0;i<int(n);i++)
#define forsn(i,s,n) for(int i=int(s);i<int(n);i++)
#define dforn(i,n) for(int i=int(n)-1;i>=0;i--)
#define dforsn(i,s,n) for(int i=int(n)-1;i>=int(s);i--)
#define fst first
#define snd second
#define pb push_back
#define eb emplace_back
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()

typedef long long ll;
typedef long double ld;
typedef vector<ll> vll;
typedef vector<int> vi;
typedef pair<int,int> ii;

const ld INF = 1e18;
const int N = 500;

template<typename T>
void chmin(T &x, T v) {
    if (x > v) x = v;
}

pair<ld, int> dp[N];

const ld EPS = 1e-1;

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    
    int n, k;
    cin >> n >> k;
    vector<pair<ll, ll>> x(n);
    forn(i, n){
        cin >> x[i].snd >> x[i].fst;
        if (x[i].fst == -1) x[i].fst = 1e9;
    }
    sort(all(x));
    ld ans = INF;
    auto check = [&](ld lmd, int c) {
        forn(a, c + 1) dp[a] = {INF, INF};
        dp[0] = {0, 0};
        forn(i, n) dforn(a, c + 1) {
            pair<ld, int> curr = dp[a];
            curr.fst += ld(x[i].fst) / (a + 1);
            chmin(dp[a + 1], curr);
            curr = dp[a];
            curr.fst += lmd + ld(x[i].snd) / (c + 1);
            curr.snd--;
            chmin(dp[a], curr);
        }
        dp[c].snd *= -1;
        dp[c].fst -= lmd * (k - c);
        return dp[c];
    };
    forn(c, k + 1) {
        ld lo = -1e11, hi = 1;
        while (hi - lo > EPS) {
            ld mid = (lo + hi) / 2;
            if (check(mid, c).snd >= k - c) lo = mid;
            else hi = mid;
        }
        chmin(ans, check(lo, c).fst);
    }
    cout << fixed << setprecision(10) << ans << '\n';
    
    return 0;
}

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