제출 #91855

#제출 시각아이디문제언어결과실행 시간메모리
91855Abelyan수열 (APIO14_sequence)C++17
100 / 100
617 ms84904 KiB
#include <bits/stdc++.h> using namespace std; #define FOR(i,a) for (int i=0;i<(a);++i) #define FORR(i,a) for (int i=(a)-1;i>=0;i--) #define FORT(i,a,b) for (int i=(a);i<=(b);++i) #define FORTR(i,a,b) for (int i=(b);i>=(a);--i) #define trav(i,v) for (auto i : v) #define fr first #define sc second #define x real #define y imag typedef long long ll; typedef long double ld; typedef complex<ll> point; const int N = 2e5+6; const int K = 406; class conv_hull{ public: vector<point> lines; vector<int> ind; int pos=0; ll f(point a, ll x) { return a.x()*x+a.y(); } ld inter(point a,point b){ ll k=a.x()-b.x(); ll c=b.y()-a.y(); //cout<<k<<endl; //cout<<c/k<<endl; return (ld)c/k; } void add_line(point nw,int index){ if (!lines.empty() && nw.x()==lines.back().x()){ return; } while (lines.size()>1){ //cout<<1<<endl; point a=lines.back(); point b=lines[lines.size()-2]; //cout<<1<<endl; if (inter(nw,b)<=inter(b,a)){ lines.pop_back(); ind.pop_back(); } else break; } lines.push_back(nw); ind.push_back(index); } pair<ll,int> get(ll x){ //cout<<pos<<" "<<lines.size()<<endl; while(pos<lines.size()-1 && inter(lines[pos],lines[pos+1])<=(ld)x){ pos++; } //cout<<lines[pos]<<endl; return {f(lines[pos],x),ind[pos]}; } void del(){ lines.clear(); ind.clear(); pos=0; } }; ll a[N],dp[N],pref[N]; int nax[K][N]; int main(){ ios_base::sync_with_stdio(false); //cout<<"hi"<<endl; int n,k; cin>>n>>k;k++; FORT (i,1,n){ cin>>a[i]; pref[i]=pref[i-1]+a[i]; } FORT(i,1,n){ dp[i]=pref[i]*pref[i]; } conv_hull t; FORT(i,2,k){ t.add_line({-2ll*pref[i-1],dp[i-1]+pref[i-1]*pref[i-1]},i-1); //cout<<-pref[i-1]<<" "<<dp[i-1][i-1]+pref[i-1]*pref[i-1]<<endl; FORT(j,i,n){ ll z=dp[j]; pair<ll,int> tv=t.get(pref[j]); dp[j]=tv.fr+pref[j]*pref[j]; nax[i][j]=tv.sc; t.add_line({-2ll*pref[j],z+pref[j]*pref[j]},j); //cout<<-2ll*pref[j]<<" "<<dp[i-1][j]+pref[j]*pref[j]<<endl; } t.del(); //cout<<endl; } cout<<(pref[n]*pref[n]-dp[n])/2ll<<endl; int tv=nax[k][n]; vector<int> v; FORTR(i,1,k-1){ v.push_back(tv); tv=nax[i][tv]; } reverse(v.begin(),v.end()); trav(ans,v)cout<<ans<<" "; return 0; } /* 7 3 4 1 3 4 0 2 3 */

컴파일 시 표준 에러 (stderr) 메시지

sequence.cpp: In member function 'std::pair<long long int, int> conv_hull::get(ll)':
sequence.cpp:58:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(pos<lines.size()-1 && inter(lines[pos],lines[pos+1])<=(ld)x){
         ~~~^~~~~~~~~~~~~~~
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