Poj2528Mayor's posters线段树

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <climits>
#include <string>
#include <iostream>
#include <map>
#include <cstdlib>
#include <list>
#include <set>
#include <queue>
#include <stack>
#include<math.h>
using namespace std;
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
const int maxn = 44444;
int color[maxn << 2];
int vis[maxn];
int q[maxn];
int q1[maxn];
int l[maxn];
int r[maxn];
int Hash[maxn];
void down(int rt)
{
    if (color[rt]){
        color[rt << 1] = color[rt << 1 | 1] = color[rt];
        color[rt] = 0;
    }
}

void build(int l, int r, int rt)
{
    color[rt] = 0;
    if (l == r) return;
    int mid = (l + r) >> 1;
    build(lson);
    build(rson);
}

void update(int L, int R, int add, int l, int r, int rt)
{
    if (L <= l&&r <= R){
        color[rt] = add; return;
    }
    down(rt);
    int mid = (l + r) >> 1;
    if (L <= mid) update(L, R, add, lson);
    if (R>mid) update(L, R, add, rson);
}

void ask(int l, int r, int rt)
{
    if (color[rt]){
        Hash[color[rt]] = 1; return;
    }
    int mid = (l + r) >> 1;
    ask(lson); ask(rson);
}

int erfen(int key, int a[], int len)
{
    int l = 0; int r = len - 1;
    while (l <= r){
        int mid = (l + r) >> 1;
        if (a[mid] == key) return mid + 1;
        if (a[mid]<key) l = mid + 1;
        if (a[mid]>key) r = mid - 1;
    }
}
int cmp(const int &a, const int &b)
{
    return a<b;
}
int main()
{
    int Icase, n;
    int ans, ans1;
    scanf("%d", &Icase);
    while (Icase--){
        ans = 0; ans1 = 0;
        memset(Hash, 0, sizeof(Hash));
        scanf("%d", &n);
        for (int i = 0; i<n; i++){
            scanf("%d%d", &l[i], &r[i]);
            q[ans++] = l[i]; q[ans++] = r[i];
        }
        sort(q, q + ans, cmp);
        memset(vis, 0, sizeof(vis));
        for (int i = 0; i<ans - 1; i++){
            if (q[i] == q[i + 1]) vis[i + 1] = 1;
        }
        int ans1 = 0;
        for (int i = 0; i<ans; i++)
        if (!vis[i]) q1[ans1++] = q[i];
        for (int i = 0; i<n; i++){
            l[i] = erfen(l[i], q1, ans1); r[i] = erfen(r[i], q1, ans1);
        }
        build(1, ans1, 1);
        for (int i = 0; i<n; i++){
            update(l[i], r[i], i + 1, 1, ans1, 1);
        }
        ask(1, ans1, 1);
        int gg = 0;
        for (int i = 1; i <= n; i++)
        if (Hash[i]) gg++;
        cout << gg << endl;
    }
    return 0;
}