Submission #1047163

#	Time	Username	Problem	Language	Result	Execution time	Memory
1047163		Sharky	Split the sequence (APIO14_sequence)	C++17	0 / 100	4 ms	4444 KiB

sequence

#pragma GCC optimize("O0")
#pragma GCC optimize("O1")
#pragma GCC optimize("O2")
#pragma GCC optimize("O3")
#pragma GCC optimize("inline")
#pragma GCC optimize("unroll-loops")

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

#define int long long
using db = long double;
const int maxn = 1E5+5;
int n, K, l = 1, r = 1, a[maxn], p[maxn], Q[maxn];
vector<int> dp, new_dp;
inline int read() {
    int x=0;char ch=getchar_unlocked();
    while (!(ch >= '0' && ch <= '9')) ch=getchar_unlocked();
    while (ch >= '0' && ch <= '9'){x=x*10+ch-48;ch=getchar_unlocked();}
    return x;
}
bool m(int j, int k, int i) {
    return ((dp[k] - dp[j]) * (p[i] - p[k])) <= ((dp[i] - dp[k]) * (p[k] - p[j]));
}

bool idk(int j, int k, int i) {
    return (p[n] - p[i]) * (p[k] - p[j]) <= (dp[k] - dp[j]);
}

int32_t main() {
    ios::sync_with_stdio(0); cin.tie(0);
    n = read(); K = read();
    new_dp.assign(n+1, 0);
    dp.assign(n+1, 0);
    for (int i = 1; i <= n; i++) {
        a[i] = read();
        p[i] = p[i-1] + a[i];
    }
    for (int i = 1; i <= n; i++) {
        dp[i] = p[i] * (p[n] - p[i]);
    }
    for (int kk = 2; kk <= K; kk++) {
        for (int i = 1; i <= n; i++) {
            Q[i] = 0;
            new_dp[i] = dp[i];
        }
        l = r = 1;
        for (int i = 1; i < kk; i++) Q[r++] = i;
        --r;
        for (int i = kk; i <= n; i++) {
            while (r - l >= 1 && idk(Q[l], Q[l+1], i)) l++;
            if (l <= r) new_dp[i] = dp[Q[l]] + (p[i] - p[Q[l]]) * (p[n] - p[i]);
            while (r - l >= 1 && m(Q[r-1], Q[r], i)) r--;
            r++; Q[r] = i;
        }
        swap(new_dp, dp);
    }
    printf("%lld\n", *max_element(dp.begin(), dp.end()));
}

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