Submission #532623

#	Time	Username	Problem	Language	Result	Execution time	Memory
532623		stefantaga	Geometrija (COCI21_geometrija)	C++14	0 / 110	1 ms	460 KiB

geometrija

#include <bits/stdc++.h>

using namespace std;
struct Punct
{
    long long x,y;
};
long long determinant (Punct a,Punct b,Punct c)
{
    return a.x*b.y+b.x*c.y+a.y*c.x-a.y*b.x-b.y*c.x-a.x*c.y;
}
bool compare (Punct a, Punct b)
{
    return a.x<b.x||(a.x==b.x&&a.y<b.y);
}
int n,i,st[4005],q,viz[4005];
Punct v[1005];
struct Triangle
{
    int a,b,c;
};
int ok[1005],primul;
vector <Triangle> triunghiuri;
int ABS(int x)
{
    if (x>0)
    {
        return x;
    }
    return -x;
}
bool seinter(pair <Punct,Punct> dreapta1,pair <Punct,Punct> dreapta2)
{
    if (determinant(dreapta1.first,dreapta1.second,dreapta2.first)*determinant(dreapta1.first,dreapta1.second,dreapta2.second)>=0)
    {
        return 0;
    }
    if (determinant(dreapta2.first,dreapta2.second,dreapta1.first)*determinant(dreapta2.first,dreapta2.second,dreapta1.second)>=0)
    {
        return 0;
    }
    return 1;
}
int Marc[1005][1005],j;
vector <pair <int,int>> candidati;
int main()
{
    ios_base :: sync_with_stdio(false);
    cin.tie(0);
#ifdef HOME
    ifstream cin("date.in");
    ofstream cout("date.out");
#endif // HOME
    cin>>n;
    for (i=1; i<=n; i++)
    {
        cin>>v[i].x>>v[i].y;
    }
    sort (v+1,v+n+1,compare);
    st[++q]=1;
    st[++q]=2;
    viz[1]=viz[2]=1;
    for (i=3; i<=n; i++)
    {
        while (q>1&&determinant(v[st[q-1]],v[st[q]],v[i])<0)
        {
            viz[st[q]]=0;
            q--;
        }
        viz[i]=1;
        st[++q]=i;
    }
    for (i=n; i>=1; i--)
    {
        if (viz[i]==0)
        {
            while (q>1&&determinant(v[st[q-1]],v[st[q]],v[i])<0)
            {
                viz[st[q]]=0;
                q--;
            }
            viz[i]=1;
            st[++q]=i;
        }
    }
    while (q>1&&determinant(v[st[q-1]],v[st[q]],v[1])<0)
    {
        q--;
    }
    for (i=1; i<=q; i++)
    {
        ok[st[i]]=1;
    }
    for (i=1; i<=n; i++)
    {
        if (ok[i]==0)
        {
            primul= i ;
            break;
        }
    }
    ok[primul]=1;
    for (i=1; i<q; i++)
    {
        triunghiuri.push_back({st[i],st[i+1],primul});
    }
    triunghiuri.push_back({st[1],st[q],primul});
    for (i=1; i<=n; i++)
    {
        if (ok[i]==0)
        {
            int loc=0;
            for (int j=0; j<triunghiuri.size(); j++)
            {
                int x=triunghiuri[j].a,y=triunghiuri[j].b,z=triunghiuri[j].c;
                int val1 = ABS(determinant(v[x],v[y],v[i]));
                int val2 = ABS(determinant(v[y],v[z],v[i]));
                int val3 = ABS(determinant(v[z],v[x],v[i]));
                int valfin = ABS(determinant(v[x],v[y],v[z]));
                if (val1+val2+val3==valfin)
                {
                    loc = j;
                    break;
                }
            }
            Triangle triunghi1= {triunghiuri[loc].a,triunghiuri[loc].b,i};
            Triangle triunghi2= {triunghiuri[loc].a,triunghiuri[loc].c,i};
            Triangle triunghi3= {triunghiuri[loc].b,triunghiuri[loc].c,i};
            triunghiuri.erase(triunghiuri.begin()+loc);
            triunghiuri.push_back(triunghi1);
            triunghiuri.push_back(triunghi2);
            triunghiuri.push_back(triunghi3);
        }
    }
    for (int j=0; j<triunghiuri.size(); j++)
    {
        int x=triunghiuri[j].a,y=triunghiuri[j].b,z=triunghiuri[j].c;
        Marc[x][y]=Marc[y][x]=Marc[x][z]=Marc[z][x]=Marc[z][y]=Marc[y][z]=1;
    }
    for (i=1; i<=n; i++)
    {
        for (j=i+1; j<=n; j++)
        {
            if (Marc[i][j])
            {
                candidati.push_back({i,j});
            }
        }
    }
    int sum=0;
    for (i=0; i<candidati.size(); i++)
    {
        int ok1=1;
        for (j=1; j<=n; j++)
        {
            for (int k=j+1; k<=n; k++)
            {
                if (seinter({v[candidati[i].first],v[candidati[i].second]}, {v[j],v[k]}))
                {
                    ok1=0;
                    break;
                }
            }
            if (ok1==0)
            {
                break;
            }
        }
        sum=sum+ok1;
    }
    cout<<sum;
    return 0;
}

Compilation message (stderr)

geometrija.cpp: In function 'int main()':
geometrija.cpp:113:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Triangle>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  113 |             for (int j=0; j<triunghiuri.size(); j++)
      |                           ~^~~~~~~~~~~~~~~~~~~
geometrija.cpp:135:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Triangle>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  135 |     for (int j=0; j<triunghiuri.size(); j++)
      |                   ~^~~~~~~~~~~~~~~~~~~
geometrija.cpp:151:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  151 |     for (i=0; i<candidati.size(); i++)
      |               ~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 20
• Subtask 2: 0 / 30
• Subtask 3: 0 / 60