Submission #380911

#	Time	Username	Problem	Language	Result	Execution time	Memory
380911		fl0rian	Tri (CEOI09_tri)	C++14	0 / 100	1 ms	364 KiB

tri

#include<bits/stdc++.h>
using namespace std;
#define MAXN 100000+10
#define rep(i,N) for(int i=0;i<N;i++)
int N,K;

typedef struct point{
    int x;
    int y;

    point(int x1,int y1){
        x=x1;
        y=y1;
    }

    point(){
    }

    //pre : no points exactly on the line
    bool isover(point * b,point * a){
        //cout << "da ("<<a->x<<","<<a->y<<") " << "a ("<<b->x<<","<<b->y<<") \n";
        int v1[2] = {b->x - a->x, b->y - a->y};
        int v2[2] = {b->x - x, b->y - y};
        int xp = v1[0]*v2[1] - v1[1]*v2[0];
        return xp>0;
    }

    bool isunder(point * a,point * b){
        return !isover(a,b);
    }

} * P;

point origin(0,0);

typedef struct triangle{

    point a;
    point b;

    bool isInside(point x){
        return x.isover(&origin,&b) && x.isunder(&origin,&a) && x.isunder(&a,&b);
    }

    bool insideTrigon(point s){
        int as_x = s.x-a.x;
        int as_y = s.y-a.y;

        bool s_ab = (b.x-a.x)*as_y-(b.y-a.y)*as_x > 0;

        if((origin.x-a.x)*as_y-(origin.y-a.y)*as_x > 0 == s_ab) return false;

        if((origin.x-b.x)*(s.y-b.y)-(origin.y-b.y)*(s.x-b.x) > 0 != s_ab) return false;

        return true;
    }

    triangle(){
    }

} * T;

vector<point> points(MAXN);
vector<triangle> triangles(MAXN);

bool solve(int t){
    rep(i,N)
        if(triangles[t].insideTrigon(points[i]))
            return true;
    return false;
}

int mi22n(){

    point a(4,4);
    point b(6,3);

    cout << "da ("<<a.x<<","<<a.y<<") " << "a ("<<b.x<<","<<b.y<<") \n";

    point a3(8,3);

    if(a3.isover(&a,&b))
        cout<<"sopra";
    else
        cout<<"sotto";
}

int main(){

    freopen("int.txt","r",stdin);

    cin>>N>>K;

    rep(i,N){
        cin >> points[i].x>> points[i].y;
        //cout << "("<<points[i].x<<","<<points[i].y<<") = " <<atan2(points[i].x,-points[i].y) << "\n";
    }

    rep(i,K){
        int q,w,e,r;
        cin>>q>>w>>e>>r;

        if(q<e){
            triangles[i].a.x=q;
            triangles[i].a.y=w;
            triangles[i].b.x=e;
            triangles[i].b.y=r;
        }else{
            triangles[i].b.x=q;
            triangles[i].b.y=w;
            triangles[i].a.x=e;
            triangles[i].a.y=r;
        }

    }

    rep(i,K)
        cout<<(solve(i)?"Y":"N")<<"\n";

    return 0;
}

Compilation message (stderr)

tri.cpp: In member function 'bool triangle::insideTrigon(point)':
tri.cpp:51:52: warning: suggest parentheses around comparison in operand of '==' [-Wparentheses]
   51 |         if((origin.x-a.x)*as_y-(origin.y-a.y)*as_x > 0 == s_ab) return false;
      |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
tri.cpp:53:62: warning: suggest parentheses around comparison in operand of '!=' [-Wparentheses]
   53 |         if((origin.x-b.x)*(s.y-b.y)-(origin.y-b.y)*(s.x-b.x) > 0 != s_ab) return false;
      |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
tri.cpp: In function 'int mi22n()':
tri.cpp:86:1: warning: no return statement in function returning non-void [-Wreturn-type]
   86 | }
      | ^
tri.cpp: In function 'int main()':
tri.cpp:90:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   90 |     freopen("int.txt","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 100