Submission #1289512

#	Time	Username	Problem	Language	Result	Execution time	Memory
1289512		Art	Feast (NOI19_feast)	C++17	100 / 100	105 ms	10996 KiB

feast

//      - Art -
#include <bits/stdc++.h>

#define el              cout << '\n'

#define FOR(i, a, b)    for (int i = (a), _b = (b); i <= _b; ++i)
#define REV(i, b, a)    for (int i = (b), _a = (a); i >= _a; --i)
#define REP(i, c)       for (int i = 0, _c = (c); i < _c; ++i)

const int N = 3e5 + 7;

using namespace std;

int n, k, a[N];

pair<long long, int> best(pair<long long, int> a, pair<long long, int> b) {
    auto &[v1, c1] = a;
    auto &[v2, c2] = b;
    if (v1 > v2) {
        return a;
    }
    else if (v1 < v2) {
        return b;
    }
    return {v1, min(c1, c2)};
}

pair<long long, int> dp[N][2]; // first: val, second: cnt
pair<long long, int> Lagrangian(long long lamda) {
    dp[0][0] = {0, 0};
    dp[0][1] = {-1e18, 0}; /// Lỗi 1: không khởi gán
    FOR (i, 1, n) {
        dp[i][0] = best(dp[i - 1][0], dp[i - 1][1]);
        dp[i][1] = best(make_pair(dp[i - 1][0].first + a[i] - lamda, dp[i - 1][0].second + 1), /// đoạn mới -> chịu phạt
                        make_pair(dp[i - 1][1].first + a[i], dp[i - 1][1].second));
    }
    return best(dp[n][0], dp[n][1]);
}

int main() {

    #define name "art"
    if (fopen(name".inp", "r")) {
        freopen(name".inp", "r", stdin);
        freopen(name".out", "w", stdout);
    }

    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);

    cin >> n >> k;
    FOR (i, 1, n) {
        cin >> a[i];
    }

    long long l = 0, r = 3e13, lamda = 0; /// lamda base = l, ko phải r
    while (l <= r) {
        long long m = l + (r - l) / 2;
        if (Lagrangian(m).second >= k) {
            l = m + 1;
            lamda = m;
        }
        else {
            r = m - 1;
        }
    }
    auto [v, c] = Lagrangian(lamda);
    cout << v + lamda * k, el;

    return 0;
}

Compilation message (stderr)

feast.cpp: In function 'int main()':
feast.cpp:44:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   44 |         freopen(name".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
feast.cpp:45:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   45 |         freopen(name".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