• Every candidate can place exactly one poster on the wall. 
• All posters are of the same height equal to the height of the wall; the width of a poster can be any integer number of bytes (byte is the unit of length in Bytetown). 
• The wall is divided into segments and the width of each segment is one byte. 
• Each poster must completely cover a contiguous number of wall segments.

/*题意：给横坐标轴染色，每次给一个区间内的染色，每染一次会把上一次的覆盖，经过n次染色只会，问你从最上面看，横坐标上总共有几种颜色初步思路：区间染色问题，就是一个区间set问题，然后最后的查询的时候，记录一下就行了#超内存：需要离散化*/#include <iostream>#include <stdio.h>#include <string.h>#include <algorithm>using namespace std;int n,l[10005],r[10005];int t;bool color[10005];//用于记录颜色int res=0;int X[20010];int k;int kk;/****************************线段树基础模板*********************************/const int maxn=20010+5;#define lson i*2, l, m#define rson i*2+1, m+1, rstruct Segtree{    int setv[maxn<<2];    void PushDown(int i)    {        if(setv[i]>0){            setv[i*2]=setv[i*2+1]=setv[i];            setv[i]=-1;//向下更新完了就没有继续用的意义了        }    }    void build(int i,int l,int r)    {        // cout<<l<<" "<<r<<" "<<i<<endl;        setv[i]=0;        if(l==r)            return ;        int m=(l+r)>>1;        build(lson);        build(rson);    }    void query(int ql,int qr,int i,int l,int r)    {        if(ql<=l&&r<=qr){            if(setv[i]>0){                color[setv[i]]=true;                return ;            }        }         if(l==r) return ;        PushDown(i);        int m=(l+r)>>1;        if(ql<=m) query(ql,qr,lson);        if(m<qr) query(ql,qr,rson);    }    void update(int ql,int qr,int val,int i,int l,int r)    {        // cout<<l<<" "<<r<<endl;        if(ql<=l&&r<=qr)        {            setv[i]=val;            return ;        }        PushDown(i);        int m=(l+r)>>1;        if(ql<=m) update(ql,qr,val,lson);        if(m<qr) update(ql,qr,val,rson);    }};Segtree segtree;/****************************线段树基础模板*********************************/void init(){    memset(color,false,sizeof color);    res=0;    k=1;    kk=1;}int findx(int key){    int l=1,r=k,mid;    while(l<=r){        mid=(l+r)>>1;        if(X[mid]==key)            return mid;        else if(X[mid]>key)            r=mid-1;        else l=mid+1;    }    return 0;}int main(){    // freopen("in.txt","r",stdin);    scanf("%d",&t);    while(t--){        init();        scanf("%d",&n);        for(int i=1;i<=n;i++){            scanf("%d%d",&l[i],&r[i]);            X[kk++]=l[i];            X[kk++]=r[i];        }        sort(X+1,X+kk+1);        for(int i=2;i<kk;i++){//离散化            if(X[i]!=X[i-1])                X[++k]=X[i];        }        segtree.build(1,1,k);        for(int i=1;i<=n;i++){            int L=findx(l[i]);            int R=findx(r[i]);            segtree.update(L,R,i,1,1,k);        }        segtree.query(1,k,1,1,k);        for(int i=1;i<=n;i++){            if(color[i]) res++;        }        printf("%d\n",res);    }    return 0;}