P4793 [AHOI2008]矩形藏宝地 cdq分治 线段树

　　

 简单题调试了半天QAQ

// luogu-judger-enable-o2
#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(ll i=(a);i<=(b);i++)
#define repp(i,a,b) for(ll i=(a);i>=(b);--i)
#define ll long long
#define see(x) (cerr<<(#x)<<'='<<(x)<<endl)
#define inf 0x3f3f3f3f
#define CLR(A,v)  memset(A,v,sizeof A)
/////////////////////////////////////
const ll N=5e6+10;
ll n,m,ans[N],xx[N],xxx[N],yy[N],yyy[N],t[N];
int nxx,nyy;
ll maxx[N<<2];
void build(int l,int r,int pos)
{
    if(!maxx[pos])return ;
    maxx[pos]=0;if(l==r)return ;
    int m=(l+r)>>1;build(l,m,pos<<1);build(m+1,r,pos<<1|1);
}
void upnode(int x,ll v,int l,int r,int pos)
{
    if(l==r){maxx[pos]=max(maxx[pos],v);return ;}
    int m=(l+r)>>1;
    if(x<=m)upnode(x,v,l,m,pos<<1);
    else upnode(x,v,m+1,r,pos<<1|1);
    maxx[pos]=max(maxx[pos<<1],maxx[pos<<1|1]);
}
ll qmax(int L,int R,int l,int r,int pos)
{
    if(L<=l&&r<=R)return maxx[pos];
    int m=(l+r)>>1;ll ans=0;
    if(L<=m)ans=max(ans,qmax(L,R,l,m,pos<<1));
    if(R>m)ans=max(ans,qmax(L,R,m+1,r,pos<<1|1));
    return ans;
}
struct node
{
    ll x1,y1,x2,y2,id;
}s[N],temp[N];
bool cmp(node a,node b){return a.y1<b.y1;}
void cdq(ll l,ll r)
{  
    if(l==r)return ;ll mid=(l+r)>>1;
    cdq(l,mid);cdq(mid+1,r);
    rep(i,l,r)temp[i]=s[i];
    sort(temp+l,temp+mid+1,cmp);sort(temp+mid+1,temp+r+1,cmp);
    ll j=l;
    build(1,nxx,1);
    rep(i,mid+1,r)
    {   
        while(j<=mid&&temp[j].y1<=temp[i].y1)upnode(temp[j].x2,temp[j].y2,1,nxx,1), j++;
        ll t=qmax(temp[i].x2,nxx,1,nxx,1);
        if(t>=temp[i].y2)ans[temp[i].id]=1;
    }
}
int main()
{
    cin>>n;
    int tot=0,tot2;
    rep(i,1,n)
    scanf("%lld%lld%lld%lld",&s[i].x1,&s[i].y1,&s[i].x2,&s[i].y2),xx[++tot]=s[i].x1,xx[++tot]=s[i].x2,
    yy[++tot2]=s[i].y1,yy[++tot2]=s[i].y2,s[i].id=i;

    sort(xx+1,xx+1+tot);sort(yy+1,yy+1+tot2);
    nxx=unique(xx+1,xx+1+tot)-xx-1;
    nyy=unique(yy+1,yy+1+tot2)-yy-1;
    
    rep(i,1,n)
    s[i].x1=lower_bound(xx+1,xx+1+nxx,s[i].x1)-xx,
    s[i].x2=lower_bound(xx+1,xx+1+nxx,s[i].x2)-xx,
    s[i].y1=lower_bound(yy+1,yy+1+nyy,s[i].y1)-yy,
    s[i].y2=lower_bound(yy+1,yy+1+nyy,s[i].y2)-yy;

    sort(s+1,s+1+n,[](node a,node b){return a.x1<b.x1;});
    cdq(1,n);
    ll cnt=0;
    rep(i,1,n)
    if(ans[i])cnt++;
    cout<<cnt<<endl;
    return 0;
}