Submission #1264618

#	Time	Username	Problem	Language	Result	Execution time	Memory
1264618		ducdev	Stove (JOI18_stove)	C++17	100 / 100	30 ms	3968 KiB

stove

// Author: 4uckd3v - Nguyen Cao Duc
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

const int MAX_N = 1e5;
const int MOD = 1e9 + 7;
const ll INF = 1e18;

template <class X, class Y>
bool minimize(X &x, const Y &y) {
    if (x <= y) return false;
    x = y;
    return true;
};

int n, k;
int a[MAX_N + 5];

namespace SUBTASK_12 {
    const int K = 5000;
    const int N = 5000;

    ll dp[K + 5][N + 5][2];

    void Solve() {
        for (int i = 0; i <= k; i++) {
            for (int j = 0; j <= n; j++) {
                dp[i][j][0] = dp[i][j][1] = INF;
            };
        };

        for (int i = 1; i <= n; i++) dp[1][i][1] = (a[i] + 1) - a[1];

        for (int i = 2; i <= k; i++) {
            for (int j = i; j <= n; j++) {
                dp[i][j][1] = min(dp[i - 1][j - 1][1] + 1, dp[i][j - 1][0] + (a[j] + 1) - a[j - 1]);
                dp[i][j][0] = min(dp[i - 1][j - 1][1], dp[i][j - 1][0] + a[j] - a[j - 1]);
            };
        };

        cout << dp[k][n][1] << '\n';
    };
};  // namespace SUBTASK_12

namespace SUBTASK_3 {
    const int K = MAX_N;
    const int N = MAX_N;

    pair<ll, int> dp[N + 5][2];

    pair<ll, int> calc(ll lambda) {
        for (int i = 0; i <= n; i++) dp[i][0] = dp[i][1] = make_pair(INF, k + 1);

        dp[1][0] = make_pair(lambda, 1);
        dp[1][1] = make_pair(lambda + 1, 1);

        for (int i = 2; i <= n; i++) {
            {
                // dp[i][1]
                if (minimize(dp[i][1].first, dp[i - 1][0].first + (a[i] + 1) - a[i - 1])) {
                    dp[i][1].second = dp[i - 1][0].second;
                };

                if (minimize(dp[i][1].first, dp[i - 1][1].first + 1 + lambda)) {
                    dp[i][1].second = dp[i - 1][1].second + 1;
                } else if (dp[i][1].first == dp[i - 1][1].first + 1 + lambda)
                    minimize(dp[i][1].second, dp[i - 1][1].second + 1);
            };

            {
                // dp[i][0]
                if (minimize(dp[i][0].first, dp[i - 1][0].first + a[i] - a[i - 1])) {
                    dp[i][0].second = dp[i - 1][0].second;
                };

                if (minimize(dp[i][0].first, dp[i - 1][1].first + lambda)) {
                    dp[i][0].second = dp[i - 1][1].second + 1;
                } else if (dp[i][0].first == dp[i - 1][1].first + lambda)
                    minimize(dp[i][0].second, dp[i - 1][1].second + 1);
            };
        };

        return dp[n][1];
    };

    void Solve() {
        ll l = 0, r = 1e15;
        ll lambda = 1e15;
        pair<ll, int> best(INF, k + 1);

        while (l <= r) {
            ll mid = (l + r) >> 1;
            pair<ll, int> calcMid = calc(mid);

            if (calcMid.second <= k) {
                lambda = mid;
                best = calcMid;
                r = mid - 1;
            } else
                l = mid + 1;
        };

        cout << best.first - lambda * max(k, best.second) << '\n';
    };
};  // namespace SUBTASK_3

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    if (fopen("MAIN.INP", "r")) {
        freopen("MAIN.INP", "r", stdin);
        freopen("MAIN.OUT", "w", stdout);
    };

    cin >> n >> k;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    };

    SUBTASK_3::Solve();
};

Compilation message (stderr)

stove.cpp: In function 'int main()':
stove.cpp:113:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  113 |         freopen("MAIN.INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
stove.cpp:114:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  114 |         freopen("MAIN.OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 30 / 30
• Subtask 3: 50 / 50