(Relax 线段树1.2)POJ 2528 Mayor's posters(计算可见线段)

/*
 * POJ_2528.cpp
 *
 *  Created on: 2013年11月25日
 *      Author: Administrator
 */

#include <iostream>
#include <cstdio>
#include <algorithm>

#define maxn 10010
#define Fup(i, s, t) for (int i = s; i <= t; i ++)

using namespace std;

bool tab[maxn];
int l[maxn], r[maxn], x[maxn * 3], num[maxn * 3], tree[maxn * 12];
int c, n;

int binary_search(int sum) {
	int l = 1, r = 3 * n;
	while (r >= l) {
		int mid = (l + r) / 2;
		if (x[mid] <= sum)
			l = mid + 1;
		else
			r = mid - 1;
	}
	return num[r];
}

void update(int i) {
	if (!tree[i])
		return;
	tree[i + i] = tree[i + i + 1] = tree[i];
	tree[i] = 0;
}

void change(int tl, int tr, int l, int r, int i, int co) {
	if (tr < l || tl > r)
		return;
	if (tl <= l && r <= tr) {
		tree[i] = co;
		return;
	}
	update(i);
	int mid = (l + r) / 2;
	change(tl, tr, l, mid, i + i, co);
	change(tl, tr, mid + 1, r, i + i + 1, co);
}

int require(int l, int r, int i) {
	int mid = (l + r) / 2;
	if (tree[i]) {
		if (!tab[tree[i]]) {
			tab[tree[i]] = 1;
			return 1;
		}
		return 0;
	}
	if (l == r)
		return 0;
	return require(l, mid, i + i) + require(mid + 1, r, i + i + 1);
}

void init() {
	scanf("%d", &n);
	Fup(i, 1, n)
	{
		scanf("%d%d", l + i, r + i);
		x[i + i + i - 2] = l[i];
		x[i + i + i - 1] = r[i];
		x[i + i + i] = (l[i] + r[i]) / 2;
	}
	sort(x + 1, x + 3 * n + 1);
	memset(num, 0, sizeof(num));
	Fup(i, 1, 3 * n)
	{
		num[i] = num[i - 1];
		if (x[i] != x[i - 1])
			num[i]++;
	}
	Fup(i, 1, n)
	{
		l[i] = binary_search(l[i]);
		r[i] = binary_search(r[i]);
	}
}

void solve(){
	memset(tree,0,sizeof(tree));
	memset(tab,0,sizeof(tab));

	int i;
	for(i = 1 ; i <= n ; ++i){
		change(l[i],r[i],1,3*n,1,i);
	}

	int ans = require(1,3*n,1);

	printf("%d\n",ans);
}


int main(){
	scanf("%d",&c);
	while(c--){
		init();
		solve();
	}

	return 0;
}