<div class="post_brief"><p>
usaco的银组都开始考这种题了么。其实还是挺水的，不过题号比较好。</p>

 

就按y排序，挨个把时间轴上的东西扔掉就完了。写离散可能还没有直接写smt快呢。

 

然后线段有一边要减1有点坑。

 

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>

using namespace std;


typedef long long dint;
#define _l (long long int)


struct cow {
int y;
int ta, tb;
};


struct node {
int l, r, w;
node ls, rs;
};
typedef pair <node, node > npr;


const int maxn = 50009;


inline bool operator <(const cow& a, const cow& b) {
return a. y < b. y;
}


int n, ans;
cow a[maxn];
node nlst[maxn << 1], *np(nlst), *rt;


node* newNode(int l, int r) {
np-> l = l;
np-> r = r;
#ifdef WIN32
np-> w = (rand() << 16) | rand();
#else
np-> w = rand();
#endif
np-> ls = np-> rs = 0;
return np ++;
}


npr split(node* p, int x) {
if (!p)
return npr(0, 0);
else if (x < p-> l) {
npr g(split(p-> ls, x));
p-> ls = g. second;
return npr(g. first, p);
}
else if (x >= p-> r) {
npr g(split(p-> rs, x));
p-> rs = g. first;
return npr(p, g. second);
}
else {
node q(newNode(p-> l, x));
q-> ls = p-> ls;
p-> ls = 0;
p-> l = x + 1;
return npr(q, p);
}
}
node merge(node p, node q) {
if (!p)
return q;
else if (!q)
return p;
else if (p-> w > q-> w) {
p-> rs = merge(p-> rs, q);
return p;
}
else {
q-> ls = merge(p, q-> ls);
return q;
}
}


int main() {
#ifndef ONLINE_JUDGE
freopen(“in.txt”, “r”, stdin);
#endif


srand(239473);
scanf("%d", &amp;n);
for (int i = 0; i &lt; n; ++ i) {
	int x, r;
	scanf("%d%d%d", &amp;x, &amp;a[i]. y, &amp;r);
	a[i]. ta = - x * r - r + 1;
	a[i]. tb = - x * r;
}
rt = newNode(-1, 1000000009);
ans = 0;
sort(a, a + n);
for (int i = 0; i &lt; n; ++ i) {
	npr x(split(rt, a[i]. ta - 1));
	npr y(split(x. second, a[i]. tb));
	if (y. first)
		++ ans;
	rt = merge(x. first, y. second);
}
printf("%d\n", ans);



}