Submission #963837

#	Time	Username	Problem	Language	Result	Execution time	Memory
963837		kh0i	Feast (NOI19_feast)	C++17	100 / 100	370 ms	26940 KiB

feast

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

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...)
#endif

using ll = long long;
using pii = pair<int, int>;

#define F first
#define S second
#define double long double
#define sz(x) (int)((x).size())
#define all(x) (x).begin(), (x).end()

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll get_rand(ll l, ll r) {
    assert(l <= r);
    return uniform_int_distribution<ll> (l, r)(rng);
}

const int N = 3e5 + 3;
const double eps = 1e-3;

int n;
pair<double, int> f[N][2];
double k, a[N];

pair<double, int> calc(double cost){
    f[0][0] = {0, 0};
    f[0][1] = {-1e15, 0};
    for(int i = 1; i <= n; ++i){
        f[i][0] = max(f[i - 1][0], f[i - 1][1]);
        f[i][1] = max((pair<double, int>){f[i - 1][0].F + a[i] - cost, f[i - 1][0].S + 1}, pair<double, int>{f[i - 1][1].F + a[i], f[i - 1][1].S});
    }
    return max(f[n][0], f[n][1]);
}

void solve(){
    cin >> n >> k;
    for(int i = 1; i <= n; ++i)
        cin >> a[i];
    double l = 0, r = 1e15;
    while(r - l > eps){
        double mid = (l + r) / 2;
        if(calc(mid).S >= k)
            l = mid;
        else
            r = mid;
    }
    pair<double, int> res = calc(l);
    cout << (ll)round(res.F + l * k);
}

int32_t main() {
    cin.tie(nullptr)->sync_with_stdio(0);
    #define task "troll"
    if(fopen(task".inp", "r")){
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    int test = 1;
//    cin >> test;
    for(int i = 1; i <= test; ++i){
//        cout << "Case #" << i << ": ";
        solve();
    }
    #ifdef LOCAL
        cerr << "\n[Time]: " << 1000.0 * clock() / CLOCKS_PER_SEC << " ms.\n";
    #endif
    return 0;
}

Compilation message (stderr)

feast.cpp: In function 'int32_t main()':
feast.cpp:62:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   62 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:63:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   63 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 8 / 8
• Subtask 3: 18 / 18
• Subtask 4: 10 / 10
• Subtask 5: 11 / 11
• Subtask 6: 20 / 20
• Subtask 7: 29 / 29