Submission #1017688

#	Time	Username	Problem	Language	Result	Execution time	Memory
1017688		vjudge1	Feast (NOI19_feast)	C++17	100 / 100	74 ms	8552 KiB

feast

#include <bits/stdc++.h>
using namespace std;
long long dp[300001][2];
int cnt[300001][2];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);

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

    long long l = 0, r = 5e10, ans;
    while (r > l) {
        long long lambda = (l+r)/2;
        dp[0][0] = 0;
        cnt[0][0] = 0;
        dp[0][1] = -1e18;
        for (int i = 1; i <= n; i++) {
            if (dp[i-1][0] > dp[i-1][1]) {
                dp[i][0] = dp[i-1][0];
                cnt[i][0] = cnt[i-1][0];
            } else {
                dp[i][0]= dp[i-1][1];
                cnt[i][0] = cnt[i-1][1];
            }

            if (dp[i-1][0] - lambda > dp[i-1][1]) {
                dp[i][1] = dp[i-1][0] - lambda + a[i];
                cnt[i][1] = cnt[i-1][0] + 1;
            } else {
                dp[i][1] = dp[i-1][1] + a[i];
                cnt[i][1] = cnt[i-1][1];
            }
        }
        double friends;
        if (dp[n][0] > dp[n][1]) {
            ans = dp[n][0] + lambda*cnt[n][0];
            friends = cnt[n][0];
        } else {
            ans = dp[n][1] + lambda*cnt[n][1];
            friends = cnt[n][1];
        }
        if (friends == k) {
            break;
        }
        if (friends > k) l = lambda+1;
        else r = lambda-1;
    }
    cout << ans;
}

• 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