Submission #364771

#	Time	Username	Problem	Language	Result	Execution time	Memory
364771		nandonathaniel	Aliens (IOI16_aliens)	C++14	100 / 100	274 ms	12516 KiB

aliens

#include "aliens.h"
#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
typedef long long LL;
typedef pair<LL,LL> pii;
typedef pair<pii,LL> piii;
vector<pii> V,point;
vector<piii> line;
LL N,M,K,dp[100005],opt[100005];

bool cmpV(pii A,pii B){
	if(A.fi!=B.fi)return A.fi<B.fi;
	return A.se>B.se;
}

pii tpot(pii satu,pii dua){
	pii jwb;
	jwb.fi=dua.se-satu.se;
	jwb.se=satu.fi-dua.fi;
	return jwb;
}

bool cmp(pii a,pii b){
	return a.fi*b.se<=a.se*b.fi;
}

LL sq(LL a){
	return a*a;
}

LL F(LL penalty){
	line.clear();
	for(LL i=1;i<=N;i++){
		LL x=V[i].se;
		LL intersect;
		if(V[i].first>V[i-1].second)intersect=0;
		else intersect=sq(V[i-1].second-V[i].first+1);
		piii now={{2*V[i].fi,-(V[i].fi*V[i].fi-2*V[i].fi+1-intersect+dp[i-1])},i-1};
		LL skg=line.size()-1,prev=line.size()-2;
		while(skg>0 && cmp(tpot(now.fi,line[skg].fi),tpot(now.fi,line[prev].fi))){
			//hapus yang gamasuk hull
			line.pop_back();
			skg--;
			prev--;
		}
		line.push_back(now);
		LL ki=1,ka=(LL)line.size()-1,add=-1e18,id;
		while(ki<=ka){
			LL mid=(ki+ka)/2;
			LL l=line[mid-1].fi.fi*x+line[mid-1].fi.se;
			LL r=line[mid].fi.fi*x+line[mid].fi.se;
			if(l>add){
				add=l;
				id=line[mid-1].se;
			}
			if(r>add){
				add=r;
				id=line[mid].se;
			}
			if(l>r)ka=mid-1;
			else ki=mid+1;
		}
		if(line.size()==1){
			add=line[0].fi.fi*x+line[0].fi.se;
//			cout << "takdir " << add << '\n';
			id=line[0].se;
		}
		dp[i]=-add+sq(V[i].se)+2*V[i].se+penalty;
		opt[i]=id;
//		cout << "yuhu " << dp[i] << " " << opt[i] << '\n';
	}
	LL noww=N,byk=0;
	while(noww!=0){
		byk++;
		noww=opt[noww];
	}
	return byk;
}

LL take_photos(int n, int m, int k, vector<int> r, vector<int> c) {
	N=(LL)n;M=(LL)m;K=(LL)k;
	for(LL i=0;i<N;i++){
		if(r[i]>c[i])swap(r[i],c[i]);
		point.push_back(make_pair((LL)r[i],(LL)c[i]));
	}
	sort(point.begin(),point.end(),cmpV);
	point.erase(unique(point.begin(),point.end()),point.end());
	V.push_back(make_pair(-1,-1));
	V.push_back(point[0]);
	pii last=point[0];
	for(LL i=1;i<N;i++){
		if(point[i].se>last.se){
			V.push_back(point[i]);
			last=point[i];
		}
	}
	N=V.size()-1;
	K=min(K,N);
	LL ki=0,ka=M*M,res;
	while(ki<=ka){
		LL mid=(ki+ka)/2;
		if(F(mid)>K)ki=mid+1;
		else{
			res=mid;
			ka=mid-1;
		}
	}
	LL hey=F(res);
	res=dp[N]-ki*k;
	return res;
}

Compilation message (stderr)

aliens.cpp: In function 'LL take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:110:5: warning: unused variable 'hey' [-Wunused-variable]
  110 |  LL hey=F(res);
      |     ^~~
aliens.cpp: In function 'LL F(LL)':
aliens.cpp:71:9: warning: 'id' may be used uninitialized in this function [-Wmaybe-uninitialized]
   71 |   opt[i]=id;
      |   ~~~~~~^~~
aliens.cpp: In function 'LL take_photos(int, int, int, std::vector<int>, std::vector<int>)':
aliens.cpp:110:10: warning: 'res' may be used uninitialized in this function [-Wmaybe-uninitialized]
  110 |  LL hey=F(res);
      |         ~^~~~~

• Subtask 1: 4 / 4
• Subtask 2: 12 / 12
• Subtask 3: 9 / 9
• Subtask 4: 16 / 16
• Subtask 5: 19 / 19
• Subtask 6: 40 / 40