Submission #352326

#	Time	Username	Problem	Language	Result	Execution time	Memory
352326		Kerim	Shortcut (IOI16_shortcut)	C++17	71 / 100	2069 ms	20204 KiB

shortcut

#include "shortcut.h"
#include "bits/stdc++.h"
#define MAXN 200009
#define INF 1000000007
#define mp(x,y) make_pair(x,y)
#define all(v) v.begin(),v.end()
#define pb(x) push_back(x)
#define wr cout<<"----------------"<<endl;
#define ppb() pop_back()
#define tr(ii,c) for(__typeof((c).begin()) ii=(c).begin();ii!=(c).end();ii++)
#define ff first
#define ss second
#define my_little_dodge 46
#define debug(x)  cerr<< #x <<" = "<< x<<endl;
using namespace std;

typedef long long ll;
typedef pair<ll,ll> PII;
template<class T>bool umin(T& a,T b){if(a>b){a=b;return 1;}return 0;}
template<class T>bool umax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
const ll B=1e18;
vector<ll>x;
vector<int>d;
int n,c;
ll cost;
map<ll,int>pm;
PII F[MAXN];
void upd(int x,ll a,ll b){
	for(;x<=c;x+=x&(-x))
		umin(F[x].ff,a),umax(F[x].ss,b);	
}
PII tap(int x){
	PII res=mp(B,-B);
	for(;x;x-=x&(-x))
		umin(res.ff,F[x].ff),umax(res.ss,F[x].ss);
	return res;	
}
set<ll>s;
bool ok(ll k){ll K=k-cost;
	ll A1=-B,A2=B,B1=-B,B2=B;
	for(int i=0;i<=c;i++)
		F[i]=mp(B,-B);
	for(int i=0;i<n;i++){
		ll xx=x[i]-d[i],yy=x[i]+d[i];
		int a=pm[xx],b=pm[yy];
		__typeof((pm).begin())it=pm.lower_bound(x[i]+d[i]-k);
		if(it!=pm.begin()){it--;
			PII res=tap(it->ss);
			umin(A2,xx+res.ff+K);
			umax(A1,yy+res.ss-K);
			umin(B2,xx-res.ss+K);
			umax(B1,yy-res.ff-K);
		}
		upd(a,xx,yy);
	}s.clear();
	for(int j=0;j<n;j++){
		ll xx=max(A1-x[j],x[j]-B2),yy=min(A2-x[j],x[j]-B1);
		if(s.lower_bound(xx)!=s.end() and *s.lower_bound(xx)<=yy)return 1;
		s.insert(x[j]);
	}
	/*
	x[i]>=A1-x[j]
	x[i]<=A2-x[j]
	x[j]-B1>=x[i]
	x[j]-B2<=x[i]
	for(int i=0;i<n;i++)
		for(int j=i+1;j<n;j++)
			if(x[j]+x[i]>=A1 and x[j]+x[i]<=A2 and x[j]-x[i]>=B1 and x[j]-x[i]<=B2)
				return 1;
	*/
	return 0;
}
long long find_shortcut(int N,vector<int> l,vector<int>D, int c_edge){
	d=D;cost=c_edge;n=N;x.resize(n);for(int i=0;i<n;i++)x[i]=0;
	for(int i=0;i<n-1;i++)
		x[i+1]=x[i]+l[i];
	for(int i=0;i<n;i++)
		pm[x[i]-d[i]]=pm[x[i]+d[i]]=1;
	tr(it,pm)it->ss=++c;
	ll st=1,en=ll(1e16);
	while(st+1<en){
		ll mid=(st+en)>>1;
		if(ok(mid))
			en=mid;
		else
			st=mid;
	}
	if(ok(st))return st;
	return en;
}

Compilation message (stderr)

shortcut.cpp: In function 'bool ok(ll)':
shortcut.cpp:45:16: warning: unused variable 'b' [-Wunused-variable]
   45 |   int a=pm[xx],b=pm[yy];
      |                ^

• Subtask 1: 9 / 9
• Subtask 2: 14 / 14
• Subtask 3: 8 / 8
• Subtask 4: 7 / 7
• Subtask 5: 33 / 33
• Subtask 6: 0 / 22
• Subtask 7: 0 / 4
• Subtask 8: 0 / 3