Submission #971074

#	Time	Username	Problem	Language	Result	Execution time	Memory
971074		Unforgettablepl	Split the sequence (APIO14_sequence)	C++17	39 / 100	2051 ms	95236 KiB

sequence

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

#define int long long

struct line{
    int m,n,idx_1,idx_2;
    line(int m,int n,int idx_1,int idx_2):m(m),n(n),idx_1(idx_1),idx_2(idx_2){}
    int operator()(int x) const{
        return x*m + n;
    }
};

long double intersection(line a,line b){
    return (long double)(a.n-b.n)/(long double)(b.m-a.m);
}

void addline(deque<line> &hull, line x){
    while(hull.size()>=2 and intersection(hull.back(),x)<=intersection(hull[hull.size()-2],hull.back()))hull.pop_back();
    hull.emplace_back(x);
}

tuple<int,int,int> get(deque<line> &hull, int x){
    while(hull.size()>=2 and hull.front()(x)<=hull[1](x))hull.pop_front();
    return {hull.front()(x),hull.front().idx_1,hull.front().idx_2};
}

int DP[100001][202];
pair<int,int> back[100001][202];
deque<line> hulls[202];
int P[100001];

int32_t main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int n,k;
    cin >> n >> k;k++;
    for(int i=1;i<=n;i++)cin>>P[i];
    for(int i=1;i<=n;i++)P[i]+=P[i-1];
//    for(int i=0;i<=k;i++)addline(hulls[i],{0,0,0,0});
    for(int i=1;i<=n;i++){
        for(int j=k;j>1;j--){
            for(int x=i-1;x>=0;x--){
                if(DP[i][j]<P[i]*P[x]-P[x]*P[x]+DP[x][j-1]){
                    DP[i][j] = P[i]*P[x]-P[x]*P[x]+DP[x][j-1];
                    back[i][j] = {x,j-1};
                }
            }
//            auto [ans,last1,last2] = get(hulls[j-1],P[i]);
//            DP[i][j] = ans;
//            back[i][j] = {last1,last2};
//            addline(hulls[j],{P[i],DP[i][j]-P[i]*P[i],i,j});
        }
    }
    cout << DP[n][k] << '\n';
    vector<int> ans;
    auto [curr1,curr2] = back[n][k];
    while(curr1 and curr2){
        ans.emplace_back(curr1);
        auto [c1,c2] = back[curr1][curr2];curr1=c1;curr2=c2;
    }
    for(int&i:ans)cout<<i<<' ';
    cout << '\n';
}

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