Submission #1246467

#	Time	Username	Problem	Language	Result	Execution time	Memory
1246467		rhombus	Feast (NOI19_feast)	C++20	0 / 100	1094 ms	35136 KiB

feast

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

#define int long long

const ll inf = 1e18;

pair <ll, int> calc(vector <int> &a, ll lambda) {
    int n = (int) a.size();
    vector dp(n + 1, vector (2, 0ll));
    vector mn(n + 1, vector (2, 0ll));
    dp[0][0] = 0;
    dp[0][1] = -inf; 
    mn[0][0] = 0;
    mn[0][1] = inf;
    for (int i = 1; i <= n; i++) {
        int x = a[i - 1];
        dp[i][0] = dp[i - 1][0];
        mn[i][0] = mn[i - 1][0];
        if (dp[i - 1][1] > dp[i][0]) {
            dp[i][0] = dp[i - 1][1];
            mn[i][0] = mn[i - 1][1];
        } else if (dp[i - 1][1] == dp[i][0]) {
            mn[i][0] = min(mn[i - 1][1], mn[i][0]);
        }
        dp[i][1] = x + dp[i - 1][1];
        mn[i][1] = mn[i - 1][1];
        if (lambda + x + dp[i - 1][0] > dp[i][1]) {
            dp[i][1] = lambda + x + dp[i - 1][0];
            mn[i][1] = mn[i - 1][0] + 1;
        } else if (lambda + x + dp[i - 1][0] == dp[i][1]) {
            mn[i][1] = min(mn[i][1], 1 + mn[i - 1][0]);
        }
        if (lambda + x + dp[i - 1][1] > dp[i][1]) {
            dp[i][1] = lambda + x + dp[i - 1][1];
            mn[i][1] = mn[i - 1][1] + 1;
        } else if (lambda + x + dp[i - 1][1] == dp[i][1]) {
            mn[i][1] = min(mn[i][1], 1 + mn[i-  1][1]);
        }
    }
    pair <ll, ll> ans;
    ans.first = max(dp[n][0], dp[n][1]);
    if (dp[n][0] == dp[n][1]) {
        ans.second = min(mn[n][0], mn[n][1]); 
    } else if (dp[n][0] > dp[n][1]) {
        ans.second = mn[n][0];
    } else {
        ans.second = mn[n][1];
    }
    return ans;
}

int32_t main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    int n, k;
    cin >> n >> k;
    vector <int> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    ll l = -1e12 - 7, r = 0;
    while (l <= r) {
        ll mid = (l + r) / 2;
        if (calc(a, mid).second <= k) {
            l = mid + 1;
        } else {
            r = mid - 1;
        }
    }
    l = -1e12 - 7;
    while (r - l > 3) {
        ll mid1 = l + (r - l) / 3;
        ll mid2 = r - (r - l) / 3;
        ll score1 = calc(a, mid1).first - calc(a, mid1).second * (ll) mid1;
        ll score2 = calc(a, mid2).first - calc(a, mid2).second * (ll) mid2;
        if (score1 <= score2) {
            l = mid1;
        } else {
            r = mid2;
        }
    }
    ll score = -inf * (ll) n;
    for (int i = l; i <= r; i++) {
        score = max(score, calc(a, i).first - calc(a, i).second * (ll) i);
    }
    cout << score << '\n';
    return 0;
}

• Subtask 1: 0 / 4
• Subtask 2: 0 / 8
• Subtask 3: 0 / 18
• Subtask 4: 0 / 10
• Subtask 5: 0 / 11
• Subtask 6: 0 / 20
• Subtask 7: 0 / 29