Submission #1209958

#	Time	Username	Problem	Language	Result	Execution time	Memory
1209958		wcarrotw	Feast (NOI19_feast)	C++17	100 / 100	137 ms	12180 KiB

feast

#include<bits/stdc++.h>
#define fi first
#define se second
#define ll long long
#define pb push_back

using namespace std;

const int N = 300005;
int n, k; ll a[N]; pair<ll, ll> dp[N][2];

pair<ll, ll> build(ll lambda) {
    memset(dp, 0, sizeof(dp));
    dp[1][0] = {0, 0};
    dp[1][1] = {a[1] - lambda, 1};
    for(ll i = 2; i <= n; ++i) {
        dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
        dp[i][1] = max(make_pair(dp[i - 1][0].fi + a[i] - lambda, dp[i - 1][0].se + 1), make_pair(dp[i - 1][1].fi + a[i], dp[i - 1][1].se));
    }
    return max(dp[n][0], dp[n][1]);
}

bool check(ll lambda) {
    return build(lambda).se >= k;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> n >> k;
    for(int i = 1; i <= n; ++i) {
        cin >> a[i];
    }
    ll lo = 0, hi = 1e18;
    while(lo < hi) {
        ll mid = (lo + hi + 1) >> 1;
        if(check(mid)) {
            lo = mid;
        } else {
            hi = mid - 1;
        }
    }
    cout << build(lo).fi + lo*k;
}

• 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