Submission #376954

#	Time	Username	Problem	Language	Result	Execution time	Memory
376954		YJU	Railway Trip (JOI17_railway_trip)	C++14	100 / 100	366 ms	51564 KiB

railway_trip

#include<bits/stdc++.h>
#pragma GCC optimize("unroll-loops,no-stack-protector,Ofast")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pll;
const ll MOD=1e9+7;
const ll MOD2=998244353;
const ll N=4e5+5;
const ld pi=acos(-1);
const ll INF=(1LL<<60);
#define SQ(i) ((i)*(i))
#define REP(i,n) for(ll i=0;i<n;i++)
#define REP1(i,n) for(ll i=1;i<=n;i++)
#define pb push_back
#define mp make_pair
#define X first
#define Y second
#define setp setprecision
#define lwb lower_bound
#define SZ(_a) (ll)_a.size()

set<ll> s;
ll n,m,q,u[N];
vector<ll> in[N];
ll r[N][20],l[N][20];

int main(){
	ios_base::sync_with_stdio(0);cin.tie(0);
	cin>>n>>m>>q;
	REP1(i,n){cin>>u[i];in[u[i]].pb(i);} 
	
	REP(j,20)r[n][j]=n,l[1][j]=1;
	for(int c=m;c>=1;c--){
		for(auto j:in[c]){
			s.insert(j);
		}
		for(auto j:in[c]){
			r[j][0]=(s.lwb(j+1)==s.end()?n:*s.lwb(j+1));
			l[j][0]=(s.lwb(j)==s.begin()?1:*prev(s.lwb(j)));
		}
	}
	for(int j=1;j<20;j++){
		REP1(i,n){
			r[i][j]=max(r[r[i][j-1]][j-1],r[l[i][j-1]][j-1]);
			l[i][j]=min(l[l[i][j-1]][j-1],l[r[i][j-1]][j-1]);
		}
	}
	while(q--){
		ll ans=0,a,b;
		cin>>a>>b;
		if(a>b)swap(a,b);
		ll L,R;
		L=R=a;
		for(int p=18;p>=0;p--){
			if(max(r[L][p],r[R][p])<b){
				ll TL=L,TR=R;
				ans+=(1<<p);
				L=min(l[TL][p],l[TR][p]),R=max(r[TR][p],r[TL][p]);
			}
		}
		ll mid=R;
		L=R=b;
		for(int p=18;p>=0;p--){
			if(min(l[L][p],l[R][p])>mid){
				ll TL=L,TR=R;
				ans+=(1<<p);
				L=min(l[TL][p],l[TR][p]),R=max(r[TR][p],r[TL][p]);
			}
		}
		cout<<ans<<"\n";
	}
	return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 15 / 15
• Subtask 3: 25 / 25
• Subtask 4: 55 / 55