Submission #31275

#	Time	Username	Problem	Language	Result	Execution time	Memory
31275		nickyrio	Split the sequence (APIO14_sequence)	C++14	0 / 100	23 ms	87576 KiB

sequence

#include <bits/stdc++.h>

using namespace std;
#define K 210
#define N 100010

    int a[N], b[N], pos[N];
    double x[N];
int n, k;
int A[N], s[N], pre[K][N];
long long dp[N];


struct Hull {

    int start, last;

    Hull(int n): start(1), last(0) {}
    void init() {
        start = 1; last = 0;
    }
    void add(int k, long long aNew, long long bNew, int pNew) {
        double xNew = -1e18;
        while(start <= last) {
            if (aNew == a[last]) {
                if (bNew >= b[last]) {
                    b[last] = bNew;
                    pos[last] = pNew;
                }
                return;
            }
            xNew = 1.0 * (b[last] - bNew) / (aNew - a[last]);
            if (start == last || xNew >= x[last]) break;
            last--;
        }
        a[++last] = aNew;
        b[last] = bNew;
        x[last] = xNew;
        pos[last] = pNew;
    }

    long long get(int k, int xQuery) {
        if (start > last) return 0;
        while (start < last && pos[start + 1] <= xQuery && x[start + 1] <= s[xQuery]) start++;
        return start;
    }

};
void trace(int k, int u) {
    if (k != 1) trace(k - 1, pre[k][u]);
    printf("%d ", u);
}

int main() {
    //freopen("SEQUENCE.inp","r",stdin);
    //freopen("SEQUENCE.out","w",stdout);
    //ios::sync_with_stdio(false);
    cin.tie(NULL);cout.tie(NULL);
    //cin>>n>>k;
    scanf("%d%d",&n, &k);
    for (int i = 1; i<=n; i++) cin>>A[i];
    for (int i = 1; i<=n; i++) s[i] = A[i] + s[i - 1];
    memset(dp, 0, sizeof dp);
    Hull CH(n);
    for (int kk = 0; kk<= k - 1; kk++) {
        for (int i = 1; i<=n; i++) {
            int tmp = CH.get(kk, i);
            pre[kk + 1][i] = pos[tmp];
            dp[i] = b[tmp] + s[i] * (a[tmp] + s[n] - s[i]);
        }
        CH.init();
        for (int i = 1; i<=n; i++) {
            CH.add(kk + 1, s[i], dp[i] - s[n] * s[i], i);
        }
    }

    long long ans = k;
    for (int i = k + 1; i<n; i++) if (dp[ans] <= dp[i]) ans = i;
    printf("%lld\n",dp[ans]);//<<endl;
    trace(k, ans);
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:60:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d",&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