Submission #1203883

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Source Code Expand

#include<vector>
#include<cmath>
#include<map>
#include<cstdlib>
#include<iostream>
#include<sstream>
#include<fstream>
#include<string>
#include<algorithm>
#include<cstring>
#include<cstdio>
#include<set>
#include<stack>
#include<bitset>
#include<functional>
#include<ctime>
#include<queue>
#include<deque>
#include<complex>
#include<cassert>
using namespace std;
#define pb push_back
#define pf push_front
typedef long long lint;
typedef complex<double> P;
#define mp make_pair
#define fi first
#define se second
typedef pair<int,int> pint;
#define All(s) s.begin(),s.end()
#define rAll(s) s.rbegin(),s.rend()
#define REP(i,a,b) for(int i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)
ostream &operator<<(ostream &os, const pint &a) { os << "(" << a.fi << "," << a.se << ")"; return os; }
ostream &operator<<(ostream &os, const vector<int> &a) {
	os<<"[";
	rep(i,a.size()){
		os<<a[i];
		if(i<a.size()-1) os<<",";
	}
	os<<"]";
	return os; 
}
#define maxv 3641919
vector<int> gr[maxv],rgr[maxv];
vector<int> vs;
bool sumi[maxv];
int cmp[maxv];
void dfs(int v){
	sumi[v]=true;
	rep(i,gr[v].size()){
		if(!sumi[gr[v][i]]) dfs(gr[v][i]);
	}
	vs.pb(v);
}
void rdfs(int v,int k){
	sumi[v]=true;cmp[v]=k;
	rep(i,rgr[v].size()){
		if(!sumi[rgr[v][i]]) rdfs(rgr[v][i],k);
	}
}
int scc(int v)
{
	memset(sumi,false,sizeof(sumi));
	vs.clear();
	rep(i,v){
		if(!sumi[i]) dfs(i);
	}
	memset(sumi,false,sizeof(sumi));
	int k=0;
	for(int i=vs.size()-1;i>=0;i--){
		if(!sumi[vs[i]]) rdfs(vs[i],k++);
	}
	return k;
}
void aedge(int v,int w){
	//cout<<v<<' '<<w<<endl;
	gr[v].pb(w);
	rgr[w].pb(v);
}
#define N 65536
int act[2][N*2+10];
//[a,b)にvから辺を貼る
void query(int a,int b,int v,int id,int k=0,int l=0,int r=N){
	//REP(i,a,b) aedge(v,i+2*n+N-1);return;
	if(r<=a || b<=l) return;
	if(a<=l && r<=b){
		//cout<<k<<endl;
		aedge(v,act[id][k]);return;
	}
	query(a,b,v,id,k*2+1,l,(l+r)/2);
	query(a,b,v,id,k*2+2,(l+r)/2,r);
}
int n;
//(id,x)に点yを貼る
void ap(int id,int x,int y){
	int k=x+N-1,pre=y;
	while(1){
		int np=n;n++;
		aedge(np,pre);
		aedge(np,act[id][k]);
		act[id][k]=np;
		pre=act[id][k];
		if(k<1) break;
		k=(k-1)/2;
	}
}
int l[51419],r[51419];
int pos[2][51419];
vector<pint> V[2];
int num[maxv],dp[maxv];
vector<int> ed[maxv];
int cal(int v){
	if(dp[v]>=0) return dp[v];
	int ret=0;
	rep(i,ed[v].size()){
		//cout<<v<<' '<<(*it)<<endl;
		if(v!=ed[v][i]) ret=max(ret,cal((ed[v][i])));
	}
	//cout<<v<<' '<<dp[v]<<endl;
	return dp[v]=ret+num[v];
}
int main()
{
	int m;
	cin>>m;
	rep(i,m) cin>>l[i];
	rep(i,m) cin>>r[i];
	rep(i,m) V[0].pb(mp(l[i]-i,i)),V[1].pb(mp(l[i]+i,i));
	sort(All(V[0]));sort(All(V[1]));
	rep(i,2) rep(j,m) pos[i][V[i][j].se]=j;
	
	n=m;
	rep(i,N*2-1){act[0][i]=n;n++;}
	rep(i,N*2-1){act[1][i]=n;n++;}
	REP(i,1,N*2-1) aedge(act[0][(i-1)/2],act[0][i]),aedge(act[1][(i-1)/2],act[1][i]);
	rep(i,m){
		query(0,lower_bound(All(V[0]),mp(r[i]-i,114514))-V[0].begin(),i,0);
		ap(0,pos[0][i],i);
		//cout<<i<<' '<<lower_bound(All(V[0]),mp(r[i]-i,114514))-V[0].begin()<<' '<<pos[0][i]<<endl;
	}
	for(int i=m-1;i>=0;i--){
		query(1,lower_bound(All(V[1]),mp(r[i]+i,114514))-V[1].begin(),i,1);
		ap(1,pos[1][i],i);
		//cout<<i<<' '<<lower_bound(All(V[1]),mp(r[i]-i,114514))-V[1].begin()<<' '<<pos[1][i]<<endl;
	}
	//rep(i,n) cout<<i<<' '<<gr[i]<<endl;
	
	int v=scc(n),out=0;
	memset(num,0,sizeof(num));memset(dp,-1,sizeof(dp));
	rep(i,m) num[cmp[i]]++;
	rep(i,n) rep(j,gr[i].size()) ed[cmp[i]].pb(cmp[gr[i][j]]);
	/*rep(i,v){
		if(ed[i].size()>0){
			sort(All(ed[i]));
			ed[i].erase(unique(All(ed[i])),ed[i].end());
		}
	}*/
	//rep(i,n) cout<<i<<' '<<cmp[i]<<endl;
	rep(i,v) out=max(out,cal(i));
	/*rep(i,v){
		vector<int> vv(ed[i].begin(),ed[i].end());
		cout<<i<<' '<<vv<<' '<<num[i]<<endl;
	}*/
	cout<<out<<endl;
}

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