POJ 2528

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <climits>
#include <string.h>
#include <queue>
#include <cmath>
#include <map>
#include <vector>
#define LL  __int64
using namespace std;
const int N=40050;
const int root=1;

int tree[N*4];
struct Paper{
	int begin,end;
}paper[N/3];
int sort_num[N],cnt;
bool hash[N/3];

void PushDown(int now){
	if(tree[now]>0){
		tree[now*2]=tree[now*2+1]=tree[now];
		tree[now]=0;
	}
}

void update(int now,int l,int r,int u,int L,int R){
	if(l<=L&&r>=R){
		tree[now]=u;
		return ;
	}
	PushDown(now);
	int m=(L+R)/2;
	if(r<=m){
		update(now*2,l,r,u,L,m);
	}
	else if(l>=m+1)update(now*2+1,l,r,u,m+1,R);
	else{
		update(now*2,l,r,u,L,m);
		update(now*2+1,l,r,u,m+1,R);
	}
}

void query(int now,int l,int r){
	if(tree[now]>0){
		if(!hash[tree[now]]) cnt++;
		hash[tree[now]]=true;
		return ;
	}
	if(l==r) return ;
	int m=(l+r)/2;
	query(now*2,l,m);
	query(now*2+1,m+1,r);
}

int Bin(int key,int n,int X[]) {  
    int l = 0 , r = n - 1;  
    while (l <= r) {  
        int m = (l + r) >> 1;  
        if (X[m] == key) return m;  
        if (X[m] < key) l = m + 1;  
        else r = m - 1;  
    }  
    return -1;  
}  

int main(){
	int T,n,tot,l,r;
	scanf("%d",&T);
	while(T--){
		scanf("%d",&n);
		tot=0;
		for(int i=1;i<=n;i++){
			scanf("%d%d",&paper[i].begin,&paper[i].end);
			sort_num[tot++]=paper[i].begin;
			sort_num[tot++]=paper[i].end;
		}
		sort(sort_num,sort_num+tot);
		int cnum=1,m=0;
		for(int i=0;i<tot;i++){
			if(i==0||sort_num[i]!=sort_num[i-1]){
				sort_num[m++]=sort_num[i];
			}
		}
       for (int i = m - 1 ; i > 0 ; i --) {  
            if (sort_num[i] != sort_num[i-1] + 1) sort_num[m ++] = sort_num[i-1] + 1;  
        }
        sort(sort_num,sort_num+m);
		memset(tree,0,sizeof(tree));
		for(int i=1;i<=n;i++){
			l=Bin(paper[i].begin , m , sort_num),r=Bin(paper[i].end , m , sort_num);
			l++,r++;
			update(root,l,r,i,1,m);
		}
		memset(hash,false,sizeof(hash));
		cnt=0;
		query(root,1,m);
		printf("%d\n",cnt);
	}
	return 0;
}