poj2525 Mayor's posters

线段树+离散化，

因为每个结点代表的不是一个点，而是一段，所以把每个线段的后端点+1，形成【x1，x2）的半开半闭区间，。。。。

code

#include <set>#include <map>#include <ctime>#include <queue>#include <cmath>#include <stack>#include <limits>#include <vector>#include <bitset>#include <string>#include <cstdio>#include <cstring>#include <fstream>#include <string.h>#include <iostream>#include <algorithm>#define Si set<int>#define LL long long#define pb push_back#define PS printf(" ")#define Vi vector<int>#define LN printf("\n")#define lson l,m,rt << 1#define rson m+1,r,rt<<1|1#define SD(a) scanf("%d",&a)#define PD(a) printf("%d",a)#define SET(a,b) memset(a,b,sizeof(a))#define FF(i,a) for(int i(0);i<(a);i++)#define FD(i,a) for(int i(a);i>=(1);i--)#define FOR(i,a,b) for(int i(a);i<=(b);i++)#define FOD(i,a,b) for(int i(a);i>=(b);i--)#define readf freopen("input.txt","r",stdin)#define writef freopen("output.txt","w",stdout)const int maxn = 50001;const long long BigP=999983;const int INF = 0x3fffffff;const int dx[]={0,1,0,-1};const int dy[]={1,0,-1,0};const double pi = acos(-1.0);const double eps= 1e-7;using namespace std;int N,M,cnt,ans1;int reg[maxn][2];int X[maxn<<2];int col[maxn<<2];bool hash[maxn];void PushDown(int rt){    if(col[rt]){        col[rt<<1]=col[rt<<1|1]=col[rt];        col[rt]=0;    }}void update(int L,int R,int c,int l,int r,int rt){    if(L<=l && R>=r){        col[rt]=c;        return;    }    PushDown(rt);    int m=(l+r)>>1;    if(L<=m) update(L,R,c,lson);    if(R>m) update(L,R,c,rson);}int BinSearch(int key){    int l=0,r=cnt;    while(l<=r){        int m=(l+r)/2;        if(X[m]==key) return m;        else if(X[m]<key){            l=m+1;        }else{            r=m-1;        }    }    return -1;}void query(int l,int r,int rt) {if (col[rt]) {    //puts("!!!!!!");if (!hash[col[rt]]) ans1++;hash[ col[rt] ] = true;return ;}if (l == r) return ;int m = (l + r) >> 1;query(lson);query(rson);}void print(int l,int r,int rt){    printf("l:%d  r:%d   col[rt]%d\n",l,r,col[rt]);    if(l==r) return ;    int m=(l+r)>>1;    print(lson);    print(rson);}int main(){    int cas;    SD(cas);    while(cas--){        SET(col,0);        SET(hash,0);        int tcnt=0;        SD(M);        FOR(i,1,M){            SD(reg[i][0]);            SD(reg[i][1]);            reg[i][1]++;            X[tcnt++]=reg[i][0];            X[tcnt++]=reg[i][1];        }        sort(X,X+tcnt);        cnt=0;        FOR(i,1,tcnt-1){            if(X[i]!=X[i-1])                X[++cnt]=X[i];        }        FOR(i,1,M){            int L=BinSearch(reg[i][0]);            int R=BinSearch(reg[i][1]);            update(L,R-1,i,0,cnt,1);        }        //print(0,cnt,1);        ans1=0;        query(0,cnt,1);        PD(ans1);LN;    }    return 0;}