Submission #1086529

#	Time	Username	Problem	Language	Result	Execution time	Memory
1086529		User0069	Split the sequence (APIO14_sequence)	C++17	71 / 100	50 ms	131072 KiB

sequence

#include<bits/stdc++.h>
#define taskname ""
#define el '\n'
#define fi first
#define sc second
#define pii pair<int, int>
#define all(v) v.begin(), v.end()
#define int long long
using namespace std;
#define Faster ios_base::sync_with_stdio(false);cin.tie(0);
const int maxn=1e5+33;
const int N=1e5;
const int mod=1e9+7;
const long long INF=1e18+2;
int n,k,a[maxn],dp[maxn][2],trace[maxn][202];
struct line
{
   int a,b,i;
};
vector<line> cht;
vector<long double> point;
long double intersect(line x,line y)
{
    return 1.0*(y.b-x.b)/(x.a-y.a);
}
void pop()
{
    cht.pop_back(),point.pop_back();
}
void add(line x)
{
    while(cht.size()&&cht.back().a==x.a) pop();
    while(cht.size()>1&&intersect(x,cht.back())<=point.back()) pop();
    if(cht.size()) point.push_back(intersect(x,cht.back()));
    else point.push_back(-INF);
    cht.push_back(x);
}
signed main()
{
    if (fopen(taskname".INP","r"))
    {
        freopen(taskname".INP","r",stdin);
        freopen(taskname".OUT","w",stdout);
    }
    Faster
    cin>>n>>k;
    k++;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
        a[i]+=a[i-1];
    }
    for(int i=2;i<=k;i++)
    {
        cht.clear();
        point.clear();
        add({a[i-1],dp[i-1][1-(i&1)]-a[i-1]*a[i-1],i-1});
        int ii=0;
        for(int j=i;j<=n;j++)
        {
            while(ii+1<cht.size()&&point[ii+1]<a[j]) ii++;
            dp[j][i&1]=cht[ii].a*a[j]+cht[ii].b;
            trace[j][i]=cht[ii].i;
            add({a[j],dp[j][1-(i&1)]-a[j]*a[j],j});
        }
    }
    cout<<dp[n][k&1]<<"\n";
    int siu=n;
    for(int i=k;i>1;i--)
    {
        cout<<trace[siu][i]<<" ";
        siu=trace[siu][i];
    }
//    cout<<"\n";
//    for(int i=1;i<=n;i++)
//    {
//        for(int j=1;j<=k;j++)
//        {
//            cout<<dp[i][j]<<" ";
//        }
//        cout<<"\n";
//    }

}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:61:23: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<line>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   61 |             while(ii+1<cht.size()&&point[ii+1]<a[j]) ii++;
      |                   ~~~~^~~~~~~~~~~
sequence.cpp:42:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   42 |         freopen(taskname".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:43:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   43 |         freopen(taskname".OUT","w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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