Submission #836429

#	Time	Username	Problem	Language	Result	Execution time	Memory
836429		Warinchai	Split the sequence (APIO14_sequence)	C++14	0 / 100	19 ms	3248 KiB

sequence

#include<bits/stdc++.h>
using namespace std;
int ar[100005];
struct line{
    long long m,c;
    int num;
    line(int mm=0,int cc=0,int i=0){
        m=mm;
        c=cc;
        num=i;
    }
    long long pnt(int x){
        return m*x+c;
    }
};
bool better(line a,line b,line c){
    return (c.c-a.c)*(a.m-b.m)<=(b.c-a.c)*(a.m-c.m);
}
struct hull{
    deque<line>dq;
    void add(line x){
        while(dq.size()>1&&better(dq[dq.size()-2],dq.back(),x)){
            dq.pop_back();
        }
        dq.push_back(x);
    }
    pair<long long,int> fbest(long long x,int mxl){
        while(dq.size()>1&&dq.front().num<mxl&&(dq.front().pnt(x)<=dq[1].pnt(x))){
            dq.pop_front();
        }
        if(dq.empty()){
            return {0,0};
        }
        return {dq.front().pnt(x),dq.front().num};
    }
}dp[205];
long long sum[100005];
int path[205][100005];
vector<int>v;
int main(){
    int n,k;
    cin>>n>>k;
    long long sm=0;
    for(int i=1;i<=n;i++){
        cin>>ar[i];
        sm+=ar[i];
        sum[i]=sm;
    }
    long long ans=0;
    long long lnum;
    //cerr<<"work"<<endl;
    for(int i=1;i<=k;i++){
        for(int j=i;j<n;j++){
            //cerr<<"i:j "<<i<<" "<<j<<endl;
            pair<long long,int>p=dp[i].fbest(sum[j],j);
            //cerr<<"after fbest"<<endl;
            long long x=p.first;
            //cerr<<"x:"<<x<<endl;
            int pn=p.second;
            long long tans=x+sm*sum[j]-sum[j]*sum[j];
            //cerr<<"ans:"<<tans<<endl;
            long long nm=sum[j];
            long long nc=tans-sm*sum[j];
            dp[i+1].add(line(nm,nc,j));
            //cerr<<"after add"<<endl;
            path[i][j]=pn;
            if(i==k){
                if(tans>ans){
                    ans=tans;
                    lnum=j;
                }
            }
        }
    }
    //cerr<<"out"<<endl;
    cout<<ans<<"\n";
    v.push_back(lnum);
    for(int i=k;i>=2;i--){
        lnum=path[i][lnum];
        v.push_back(lnum);
    }
    for(int i=v.size()-1;i>=0;i--){
        cout<<v[i]<<" ";
    }

}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:77:16: warning: 'lnum' may be used uninitialized in this function [-Wmaybe-uninitialized]
   77 |     v.push_back(lnum);
      |     ~~~~~~~~~~~^~~~~~

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