Submission #301746

#	Time	Username	Problem	Language	Result	Execution time	Memory
301746		ansol4328	Split the sequence (APIO14_sequence)	C++14	100 / 100	1053 ms	84560 KiB

sequence

#include<bits/stdc++.h>

using namespace std;
typedef long long ll;

struct line{
    ll slope, constant;
    int num;
    line() : slope(0), constant(0), num(0) {}
    line(ll a, ll b, int c) : slope(a), constant(b), num(c) {}
};

struct CHT{
    int sz;
    deque<line> L;
    CHT() : sz(0) {}
    double get_point(line L1, line L2){
        return (double)(L2.constant-L1.constant)/(L1.slope-L2.slope);
    }
    bool increase(line L1, line L2, line L3){
        double p1=get_point(L1,L2);
        double p2=get_point(L2,L3);
        return p1<=p2;
    }
    void update(line L3){
        while(sz>1){
            line L2=L.back();
            L.pop_back();
            sz--;
            line L1=L.back();
            if(increase(L1,L2,L3)){
                L.push_back(L2);
                sz++;
                break;
            }
        }
        L.push_back(L3);
        sz++;
    }
    ll query(ll x){
        while(sz>1 && get_point(L[0],L[1])<(double)x){
            L.pop_front();
            sz--;
        }
        line L1=L.front();
        return L1.slope*x+L1.constant;
    }
    int get_line_num(){
        line L1=L.front();
        return L1.num;
    }
    void clr(){
        while(!L.empty()) L.pop_back();
        sz=0;
    }
};

int n, k;
ll sum[100005];
ll dp[100005];
int path[205][100005];
CHT cht[2];

int main()
{
    scanf("%d %d",&n,&k);
    for(int i=1 ; i<=n ; i++){
        scanf("%lld",&sum[i]);
        sum[i]+=sum[i-1];
    }
    k++;
    cht[0].update(line(0,0,0));
    for(int i=1 ; i<=k ; i++){
        int prev=(i-1)%2;
        int cur=i%2;
        cht[cur].clr();
        for(int j=i ; j<=n ; j++){
            ll val=cht[prev].query(sum[j]);
            dp[j]=val+sum[n]*sum[j]-sum[j]*sum[j];
            path[i][j]=cht[prev].get_line_num();
            cht[cur].update(line(sum[j],dp[j]-sum[n]*sum[j],j));
        }
    }
    printf("%lld\n",dp[n]);
    int res[205];
    int cnt=k;
    res[k]=n;
    while(cnt!=1){
        res[cnt-1]=path[cnt][res[cnt]];
        cnt--;
    }
    for(int i=1 ; i<k ; i++) printf("%d ",res[i]);
    return 0;
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:66:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   66 |     scanf("%d %d",&n,&k);
      |     ~~~~~^~~~~~~~~~~~~~~
sequence.cpp:68:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   68 |         scanf("%lld",&sum[i]);
      |         ~~~~~^~~~~~~~~~~~~~~~

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