Submission #1138520

#	Time	Username	Problem	Language	Result	Execution time	Memory
1138520		anmattroi	수열 (APIO14_sequence)	C++17	0 / 100	0 ms	320 KiB

sequence

#include <bits/stdc++.h>
#define maxn 100005
using namespace std;

struct line {
    int a; int64_t b;
    line() {}
    line(int _a, int64_t _b) : a(_a), b(_b) {}

    long double intersectX(const line &other) const {
        return (long double) (b-other.b) / (other.a-a);
    }
};

int64_t f(line x, int y) {
    return 1LL * x.a * y + x.b;
}

int n, k;
int a[maxn], s[maxn];
int64_t dp[maxn][205];

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

    cin >> n >> k;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        s[i] = s[i-1] + a[i];
    }
    ++k;
    for (int i = 1; i <= n; i++) dp[i][0] = LLONG_MIN;

    for (int c = 1; c <= k; c++) {
        deque<line> dq;
        dq.push_back({0, 0});
        for (int i = 1; i <= n; i++) {
            while (dq.size() >= 2 && f(dq[0], s[i]) <= f(dq[1], s[i])) dq.pop_front();
            dp[i][c] = f(dq[0], s[i]);
            if (dp[i][c-1] == LLONG_MIN) continue;
            line cur = line(s[i], dp[i][c-1] - 1LL * s[i] * s[i]);
            if (dq.back().a == cur.a) {
                if (dq.back().b >= cur.b) continue;
                dq.pop_back();
            }
            while (dq.size() >= 2 && dq.back().intersectX(cur) <= dq.back().intersectX(dq[dq.size()-2])) dq.pop_back();
            dq.push_back(cur);
        }
    }
    cout << dp[n][k];

}

• Subtask 1: 0 / 11
• Subtask 2: 0 / 11
• Subtask 3: 0 / 11
• Subtask 4: 0 / 17
• Subtask 5: 0 / 21
• Subtask 6: 0 / 29