Cod sursa(job #1386360)

Utilizator retrogradLucian Bicsi retrograd Data 12 martie 2015 22:01:39
Problema Poligon Scor 0
Compilator cpp Status done
Runda Arhiva de probleme Marime 1.92 kb
#include<fstream>
#include<vector>

using namespace std;
typedef double var;

ifstream fin("poligon.in");
ofstream fout("poligon.out");

struct Punct {
    var x, y;
    Punct(var a, var b) {
        x = a;
        y = b;
    }
};

bool intersect(Punct a, Punct b, Punct c, Punct d) {
    var x1 = a.x, x2 = b.x, x3 = c.x, x4 = d.x;
    var y1 = a.y, y2 = b.y, y3 = c.y, y4 = d.y;

    var A1 = y2-y1, B1 = x1-x2, C1 = y1*x2-y2*x1;
    var A2 = y4-y3, B2 = x3-x4, C2 = y3*x4-y4*x3;

    //fout<<A1<<" "<<B1<<" "<<C1<<'\n';
    //fout<<A2<<" "<<B2<<" "<<C2<<'\n';

    var delta = B1*A2 - B2*A1;
    if(delta == 0) return false;

    var x = (C1*B2 - C2*B1)/delta;
    var y = (C2*A1 - C1*A2)/delta;


    if(x1 > x2) swap(x1, x2);
    if(y1 > y2) swap(y1, y2);
    if(x3 > x4) swap(x3, x4);
    if(y3 > y4) swap(y3, y4);

    return (y1 <= y && y <= y2 && x1 <= x && x <= x2 &&
            y3 <= y && y <= y4 && x3 <= x && x <= x4);


    //fout<<x<<" "<<y<<'\n';

    //ecuatia dreptei ab
}

vector<Punct> Poligon;

int main() {
    int n, m;
    var x, y;

    fin>>n>>m;
    for(int i=1; i<=n; i++) {
        fin>>x>>y;
        Poligon.push_back(Punct(x, y));
    }

    Punct INF[] = {
        Punct (666013, 100003),
        Punct (3298712, 209829),
        Punct (2918242, 1230981)
    };

    int sum = 0;

    for(int i=1; i<=m; i++) {
        int count = 0;
        fin>>x>>y;
        Punct p(x, y);

        for(int j=1; j<n; j++) {
            int res = 0;
            for(int t=0; t<3; t++) {
                res += (intersect(p, INF[t], Poligon[j], Poligon[j+1]))%2;
            }
            count += (res >= 2);
        }

        int res = 0;
        for(int t=0; t<3; t++) {
            res += (intersect(p, INF[t], Poligon[0], Poligon[n-1]))%2;
        }
        count += (res >= 2);

        sum += (count % 2);

    }

    fout<<sum;

    return 0;
}