poj 2528 poster经典线段树+lazy+离散化

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int maxn=10010;
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
int a[maxn];int b[maxn];int x[maxn*3];int flag[maxn];
int cor[maxn<<4];
int cnt=0;
int trans(int num,int l,int r)
{
   // int m=(l+r)>>1;
  //  if(num==x[m]) return m;
  //  if(num>x[m]) return trans(num,m+1,r);
   // if(num<trans) return trans(num,l,m);
    while(l<=r)
    {
        int m=(l+r)>>1;
        if(x[m]==num) return m;
        if(num>x[m]) l=m+1;
        else r=m;
    }
    return -1;
}
void pushdown(int rt)
{
    if(cor[rt]!=-1)
    {
        cor[rt<<1]=cor[rt];
        cor[rt<<1|1]=cor[rt];
        cor[rt]=-1;
    }
}
void update(int a,int b,int i,int l,int r,int rt)
{
    if(a<=l&&b>=r)
    {
        cor[rt]=i;
        return;
    }
    pushdown(rt);
    int m=(r+l)>>1;
    if(a<=m) update(a,b,i,lson);
    if(b>m) update(a,b,i,rson);
}
void query(int l,int r,int rt)
{
    if(cor[rt]!=-1)
    {
        if(!flag[cor[rt]])
        {
            cnt++;
            flag[cor[rt]]=1;
        }
        return;
    }
    if(l==r) return;
    int m=(r+l)>>1;
    query(lson);
    query(rson);
}
int main()
{
    int cases,n;
    scanf("%d",&cases);
    while(cases--)
    {
        scanf("%d",&n);
        memset(cor,-1,sizeof(cor));
        int pointer=0;
        for(int i=0;i<n;i++)
        {
            scanf("%d%d",&a[i],&b[i]);
            x[pointer++]=a[i];
            x[pointer++]=b[i];
        }
        sort(x+1,x+pointer);
        int pointer2=1;
        for(int i=1;i<pointer;i++)
        {
            if(x[i]!=x[i-1]) x[pointer2++]=x[i];
        }
        for(int i=pointer2-1;i>=0;i--)
        {
            if(x[i]!=x[i-1]+1) x[pointer2++]=x[i-1]+1;
        }
        sort(x,x+pointer2);
        for(int i=0;i<n;i++)
        {
            int l=trans(a[i],0,pointer2-1);
            int r=trans(b[i],0,pointer2-1);
            update(l,r,i,0,pointer2-1,1);
        }
        cnt=0;
        memset(flag,0,sizeof(flag));
        query(0,pointer2-1,1);
        printf("%d
",cnt);
    }
    return 0;
}