Submission #206099

#	Time	Username	Problem	Language	Result	Execution time	Memory
206099		TAISA_	Bulldozer (JOI17_bulldozer)	C++14	0 / 100	9 ms	1148 KiB

bulldozer

#include <bits/stdc++.h>
#define all(v) v.begin(),v.end()
#define eb emplace_back
using namespace std;
using ll=long long;
using P=pair<int,int>;
void chmax(ll &a,ll b){a=max(a,b);}
void chmin(ll &a,ll b){a=min(a,b);}
struct segtree{
	struct T{
		ll l,r,sum,val;
	};
	T merge(T &a,T &b){
		T res;
		res.l=max(a.l,a.sum+b.l);
		res.r=max(b.r,a.r+b.sum);
		res.sum=a.sum+b.sum;
		res.val=max({a.val,b.val,a.r+b.l});
		return res;
	}
	int n;
	vector<T> dat;
	segtree(int n_){
		n=1;
		while(n<n_)n<<=1;
		dat.resize(2*n,T{0,0,0,0});
	}
	void upd(int k,ll x){
		T to=T{max(x,0LL),max(x,0LL),x,max(x,0LL)};
		k+=n;
		dat[k]=to;
		k>>=1;
		while(k>0){
			dat[k]=merge(dat[k<<1],dat[k<<1|1]);
			k>>=1;
		}
	}
	inline ll get(){
		return dat[1].val;
	}
};
const double eps=1e-9;
bool equal(double a,double b){return a-eps<=b&&b<=a+eps;}
int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	int n;cin>>n;
	vector<double> x(n),y(n);
	vector<ll> w(n);
	vector<pair<double,P>> v;
	vector<pair<P,int>> ps(n);
	for(int i=0;i<n;i++){
		cin>>x[i]>>y[i]>>w[i];
		ps[i]=make_pair(P(y[i],x[i]),i);
	}
	for(int i=0;i<n;i++){
		for(int j=0;j<n;j++){
			if(i==j)continue;
			double t=atan2(y[j]-y[i],x[j]-x[i]);
			if(t>=0){
				v.eb(t,P(i,j));
			}
		}
	}
	sort(all(v));
	sort(all(ps));
	reverse(all(ps));
	segtree seg(n);
	vector<int> pos(n);
	for(int i=0;i<n;i++){
		seg.upd(i,w[ps[i].second]);
		pos[ps[i].second]=i;
	}
	ll res=seg.get();
	vector<vector<int>> G(n);
	vector<int> in(n);
	set<int> st;
	for(int i=0;i<v.size();i++){
		int l=v[i].second.first,r=v[i].second.second;
		G[l].eb(r);
		in[r]++;
		st.insert(l);
		st.insert(r);
		if(i+1<v.size()&&equal(v[i].first,v[i+1].first))continue;
		vector<int> rt;
		for(auto &e:st){
			if(in[e]==0)rt.eb(e);
		}
		assert(st.size()==2);
		assert(rt.size()==1);
		for(auto &ro:rt){
			int id=ro;
			vector<int> vs;
			vs.eb(ro);
			while(!G[id].empty()){
				int to;
				for(auto &e:G[id]){
					in[e]--;
					if(in[e]==0){
						to=e;
					}
				}
				vs.eb(to);
				id=to;
			}
			assert(vs.size()==2);
			int sz=vs.size();
			for(int j=0;j<sz;j++){
				if(sz-j-1<=j)break;
				int a=vs[j],b=vs[sz-j-1];
				swap(pos[a],pos[b]);
				seg.upd(pos[a],w[a]);
				seg.upd(pos[b],w[b]);
			}
		}
		for(auto &e:st){
			in[e]=0;
			G[e].clear();
		}
		st.clear();
		chmax(res,seg.get());
	}
	cout<<res<<'\n';
}

Compilation message (stderr)

bulldozer.cpp: In function 'int main()':
bulldozer.cpp:78:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<v.size();i++){
              ~^~~~~~~~~
bulldozer.cpp:84:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(i+1<v.size()&&equal(v[i].first,v[i+1].first))continue;
      ~~~^~~~~~~~~

• Subtask 1: 0 / 5
• Subtask 2: 0 / 20
• Subtask 3: 0 / 35
• Subtask 4: 0 / 20
• Subtask 5: 0 / 20