Submission #1128872

#	Time	Username	Problem	Language	Result	Execution time	Memory
1128872		8pete8	Gift Exchange (JOI24_ho_t4)	C++20	100 / 100	1586 ms	85272 KiB

Main

#include<iostream>
#include<stack>
#include<map>
#include<vector>
#include<string>
#include<unordered_map>
#include <queue>
#include<cstring>
#include<limits.h>
#include <cassert>
#include <cstdint>
#include<cmath>
#include<set>
#include<algorithm>
#include <iomanip>
#include<numeric> //gcd(a,b)
#include<bitset>
#define ll long long
#define f first
#define endl "\n"
#define s second
#define pii pair<int,int>
#define ppii pair<int,pii>
#define vi vector<int>
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define F(n) for(int i=0;i<n;i++)
#define lb lower_bound
#define ub upper_bound
#define fastio ios::sync_with_stdio(false);cin.tie(NULL);
#pragma GCC optimize ("03,unroll-loops")
using namespace std;
//#define int long long
#define double long double
const int mod=1e9+7,mxn=5e5+5,lg=30,inf=1e9,minf=-1e9;
int n,A[mxn+10],B[mxn+10],add[mxn+10],mode=0,base=minf,L[mxn+10],R[mxn+10],q,ans[mxn+10];
int comb(int a,int b){
	if(mode)return min(a,b);
	return max(a,b);
}
struct seg{
	int v[8*mxn+10],lazy[8*mxn+10];
	void init(){for(int i=0;i<=8*n;i++)v[i]=lazy[i]=base;}
	void push(int l,int r,int pos){
		v[pos]=comb(v[pos],lazy[pos]);
		if(l!=r){
			lazy[pos*2]=comb(lazy[pos],lazy[pos*2]);
			lazy[pos*2+1]=comb(lazy[pos],lazy[pos*2+1]);
		}
		lazy[pos]=base;
	}
	void update(int l,int r,int pos,int ql,int qr,int val){
		push(l,r,pos);
		if(l>qr||r<ql)return;
		if(ql<=l&&r<=qr){
			lazy[pos]=val;
			push(l,r,pos);
			return;
		}
		int mid=l+(r-l)/2;
		update(l,mid,pos*2,ql,qr,val);
		update(mid+1,r,pos*2+1,ql,qr,val);
		v[pos]=comb(v[pos*2],v[pos*2+1]);
	}
	void updatepos(int l,int r,int pos,int qpos,int val){
		push(l,r,pos);
		if(l==r)return void(v[pos]=val);
		int mid=l+(r-l)/2;
		if(qpos<=mid)updatepos(l,mid,pos*2,qpos,val);
		else updatepos(mid+1,r,pos*2+1,qpos,val);
		v[pos]=comb(v[pos*2],v[pos*2+1]);
	}
	int qry(int l,int r,int pos,int ql,int qr){
		push(l,r,pos);
		if(l>qr||r<ql)return base;
		if(ql<=l&&r<=qr)return v[pos];
		int mid=l+(r-l)/2;
		return comb(qry(l,mid,pos*2,ql,qr),qry(mid+1,r,pos*2+1,ql,qr));
	}
}t;
//mode 0 = max
//mode 1 =min
vector<pii>ask[mxn+10];
vector<int>deact[mxn+10];
int32_t main(){
	fastio
	cin>>n;
	for(int i=1;i<=n;i++)cin>>A[i];
	for(int i=1;i<=n;i++)cin>>B[i];
	t.init();
	//get L
	for(int i=1;i<=n;i++){
		L[i]=t.qry(1,2*n,1,B[i],A[i]);
		if(L[i]==minf)L[i]=0;
		L[i]++;
		t.update(1,2*n,1,B[i],A[i],i);
	}
	mode=1,base=inf;
	t.init();
	for(int i=n;i>=1;i--){
		R[i]=t.qry(1,2*n,1,B[i],A[i]);
		if(R[i]==inf)R[i]=n+1;
		R[i]--;
		deact[L[i]].pb(i);
		t.update(1,2*n,1,B[i],A[i],i);
		
	}
	cin>>q;
	for(int i=0;i<q;i++){
		int l,r;cin>>l>>r;
		ask[l].pb({r,i});
	}
	mode=0,base=minf;
	t.init();
	for(int cl=n;cl>=1;cl--){
		t.updatepos(1,n,1,cl,R[cl]);
		for(auto j:ask[cl])ans[j.s]=(t.qry(1,n,1,cl,j.f)<j.f);
		for(auto j:deact[cl])t.updatepos(1,n,1,j,minf);
	}
	for(int i=0;i<q;i++)cout<<((ans[i])?"Yes\n":"No\n");
}
/*
we can make a sub group/component (each range(B,A) intersects at least 1 range in the group)
if we start at the min Ai we can try moving up to max Aj then we can start moving down from max Aj -> min Ai
if we cant move Ai->Aj then its not a sub group

if there exist a sub group with only 1 member then that member is forced to give the gift to himself which is not allow
so the answer will be no

we can then find L and R of each student where atleast 1 range will intersects them
we can use sweep line + lazy seg for precompute L,R

for qry sweep line L update at pos=i with val=R
when Lcur<L we deactivate
for qry just check if max(l,r)>r
*/

• Subtask 1: 4 / 4
• Subtask 2: 5 / 5
• Subtask 3: 10 / 10
• Subtask 4: 31 / 31
• Subtask 5: 8 / 8
• Subtask 6: 12 / 12
• Subtask 7: 18 / 18
• Subtask 8: 12 / 12