Submission #72512

#	Time	Username	Problem	Language	Result	Execution time	Memory
72512		IDxTree (#118)	Hill Reconstruction (FXCUP3_hill)	C++17	32 / 100	1516 ms	38224 KiB

hill

#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;
const int inf=2e9, MX=300010;

struct edge{
	ll x=1, y=0;
	bool operator > (const edge &e) const {
		return y*e.x>e.y*x;
	}
	bool operator == (const edge &e) const {
		return y*e.x==e.y*x;
	}
};

edge E[MX];

struct node{
	int idx;
	bool operator > (const node &nd) const {
		int a=idx, b=nd.idx;
		ll p=E[a].y*E[b].x, q=E[b].y*E[a].x;
		return p>q || (p==q && a > b);
	}
};

set<int> S1;
set<node, greater<node>> S2;

int n;
ll X[MX], Y[MX];
ll c;

int gcd(int x, int y){
	if(y==0) return x;
	return gcd(y,x%y);
}

inline ll area(int l, int r){
	return (X[r]-X[l])*(Y[l]+Y[r]);
}

int main(){
	ios::sync_with_stdio(0); cin.tie(0);
	cin>>n>>c; c*=2;
	for(int i=1; i<=n; i++) cin>>X[i];
	for(int i=1; i<=n; i++) cin>>Y[i];
	for(int i=1; i<n; i++){
		edge e;
		e.x=X[i+1]-X[i];
		e.y=Y[i+1]-Y[i];
		E[i]=e;
	}
	for(int i=1; i<n; i++){
		S1.insert(i);
		S2.insert({i});
	}
	while(true){
		int i=S2.begin()->idx;
		if(i==1) break;

		int j=*prev(S1.find(i));

		int k=n;
		auto it=S1.find(i);
		if(next(it)!=S1.end()) k=*next(it);

		ll now=area(j,k)-area(j,i)-area(i,k);

		if(now>c) break;

//		cout<<"POINTS: "<<j<<' '<<i<<' '<<k<<'\n';

		c-=now;

		S1.erase(i), S2.erase({i});
		S1.erase(j), S2.erase({j});

		edge g; g.x=E[i].x+E[j].x, g.y=E[i].y+E[j].y;
		E[j]=g; S1.insert(j), S2.insert({j});
//		cout<<S1.size()<<", "<<S2.size()<<'\n';
	}
	{
		edge ans=E[S2.begin()->idx];
		int x=ans.x, y=ans.y, g=gcd(x,y);
		cout<<y/g<<"/"<<x/g<<'\n';
	}
	return 0;
}

• Subtask 1: 32 / 32
• Subtask 2: 0 / 68