线段树典型例题--poj2528

3
1 10
1 3
6 10

#include <iostream>
#include <cstring>
#include <string>
#include <cstdio>
#include <algorithm>
using namespace std;

const int N=10005;

int a
,b
,col[N*10],g[N*3];
bool v
,pp[N*10];
int ans,tot,n,cc;

void down(int i)
{
if (!pp[i]) return;
col[i*2]=col[i*2+1]=col[i];
pp[i*2]=pp[i*2+1]=true;
pp[i]=false;
}

void ins(int i,int l,int r,int x,int y,int c)
{
if (x<=l && y>=r)
{
col[i]=c;
pp[i]=true;
return;
}
down(i);
int mid=(l+r)>>1;
if (x<=mid) ins(i*2,l,mid,x,y,c);
if (y>mid) ins(i*2+1,mid+1,r,x,y,c);
if (col[i*2]!=col[i*2+1] || col[i*2]==-1 || col[i*2+1]==-1)
col[i]=-1;
}

int get(int i,int l,int r,int x)
{
if (col[i]!=-1) return col[i];
down(i);
int mid=(l+r)>>1;
if (x<=mid) return get(i*2,l,mid,x);
else return get(i*2+1,mid+1,r,x);
}

int main()
{
int i;

freopen("in","r",stdin);
scanf("%d",&cc);
while (cc--)
{
memset(col,0,sizeof(col));
memset(pp,0,sizeof(pp));
memset(v,0,sizeof(v));
tot=ans=0;
scanf("%d",&n);
for (i=1;i<=n;i++)
{
scanf("%d%d",&a[i],&b[i]);
g[tot++]=a[i];
g[tot++]=b[i];
if (a[i]>1) g[tot++]=a[i]-1;
}
sort(g,g+tot);
tot=unique(g,g+tot)-g;
for (i=1;i<=n;i++)
{
a[i]=lower_bound(g,g+tot,a[i])-g+1;
b[i]=lower_bound(g,g+tot,b[i])-g+1;
ins(1,1,tot,a[i],b[i],i);
}
for (i=1;i<=tot;i++)
v[get(1,1,tot,i)]=true;
for (i=1;i<=n;i++)
ans+=v[i];
printf("%d\n",ans);
}
}