Submission #331180

#	Time	Username	Problem	Language	Result	Execution time	Memory
331180		couplefire	Split the sequence (APIO14_sequence)	C++17	71 / 100	1304 ms	82284 KiB

sequence

#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define MAXN 100005
#define INF 1000000000000000000ll

int n, kk;
int h, t;
long long sum[MAXN];
int arr[MAXN];
long long dp[MAXN][2];
int where[MAXN][201];

long long X(int i){
    return sum[i];
}

long long Y(int i){
    return sum[i]*sum[i]-dp[i][0];
}

long double slope(int i, int j){
    if(X(i) == X(j)) return Y(j) > Y(i) ? INF : -INF;
    return (0.0+Y(j)-Y(i))/(0.0+X(j)-X(i));
}

long long cost(int i, int j){
    return dp[j][0]+sum[i]*sum[j]-sum[j]*sum[j];
}

int main(){
    // freopen("a.in", "r", stdin);
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cin >> n >> kk;
    for(int i = 1; i<=n; i++) cin >> arr[i];
    for(int i = 1; i<=n; i++) sum[i] = sum[i-1]+arr[i];
    for(int k = 1; k<=kk; k++){
        h = 1, t = 0;
        int hull[n+5];
        fill(hull, hull+n+5, 0);
        hull[++t] = 0;
        dp[0][1] = 0;
        for(int i = 1; i<=n; i++){
            while(h < t && slope(hull[h], hull[h+1]) <= (long double) sum[i]) ++h;
            where[i][k] = hull[h];
            dp[i][1] = cost(i, hull[h]);
            while(h < t && slope(hull[t-1], hull[t]) >= slope(hull[t], i)) --t;
            hull[++t] = i;
        }
        for(int i = 0; i<=n; i++) dp[i][0] = dp[i][1];
    }
    cout << dp[n][1] << endl;
    int cur = n;
    for(int k = kk; k>=1; --k){
        cout << where[cur][k] << " ";
        cur = where[cur][k];
    }
}

Compilation message (stderr)

sequence.cpp:2: warning: ignoring #pragma GCC optimization [-Wunknown-pragmas]
    2 | #pragma GCC optimization ("O3")
      | 
sequence.cpp:3: warning: ignoring #pragma GCC optimization [-Wunknown-pragmas]
    3 | #pragma GCC optimization ("unroll-loops")
      |

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