Cod sursa(job #2406412)

Utilizator CiprianC11Constantinescu Ciprian CiprianC11 Data 15 aprilie 2019 18:50:20
Problema Rays Scor 10
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 1.32 kb
#include <bits/stdc++.h>

using namespace std;

struct s { double p; bool t; };

const double pi = 2.0 * acos(0.0), e = 1e-14;

bool cmp(s a, s b) { if(fabs(a.p - b.p) < e) return a.t > b.t; return a.p - b.p < -e; };

vector<s> v;

const int mx = 3e6;
int p;

char b[mx];

int scan()
{
    int nr = 0, f = 1;
    while(b[p] != '-' and !('0' <= b[p] and b[p] <= '9')) p++;
    if(b[p] == '-') f = -1, p++;
    while('0' <= b[p] and b[p] <= '9') nr = nr * 10 + b[p] - '0', p++;
    return f * nr;
}

int main()
{
    freopen("rays.in", "r", stdin);
    freopen("rays.out", "w", stdout);
    int x, y1, y2, n, cnt = 0, ans = 0;
    bool t = 0;
    fread(b, 1, mx, stdin);
    n = scan();
    for(int i = 0; i < n; i++)
    {
        x = scan(), y1 = scan(), y2 = scan();
        if(y1 > y2) swap(y1, y2);
        v.push_back({atan2(y1, x) - pi / 2, 1});
        if(v.back().p <= e) v.back().p += 2 * pi;
        if(v.back().p - pi <= e) v.back().t = 0;
        v.push_back({atan2(y2, x) - pi / 2, 0});
        if(v.back().p <= e) v.back().p += 2 * pi;
        if(v.back().p - pi <= e) v.back().t = 1;
    }
    sort(v.begin(), v.end(), cmp);
    for(int i = 0; i < v.size(); i++)
    {
        if(v[i].t) cnt++, t = 0;
        else cnt--, ans += !t, t = 1;
    }
    printf("%d", ans);
    return 0;
}