[poj] 2318 TOYS || 判断点在多边形内

#include<cstdio>
#include<algorithm>
#include<cstring>
#define N 5050
using namespace std;
int n,m,ans[N];

int Read()
{
    int ans=0,fu=1;
    char j=getchar();
    for (;j<'0' || j>'9';j=getchar()) if (j=='-') fu=-1;
    for (;j>='0' && j<='9';j=getchar()) ans*=10,ans+=j-'0';
    return ans*fu;
}

struct point
{
    int x,y;
    point() {}
    point(int _x,int _y) : x(_x),y(_y) {}
    bool operator == (const point &b) const
    {
        return x==b.x && y==b.y;
    }
    bool operator < (const point &b) const
    {
        if (x==b.x) return y<b.y;
        return x<b.x;
    }
    point operator - (const point &b) const
    {
        return point(b.x-x,b.y-y);
    }
    double operator * (const point &b) const
    {
        return x*b.y-b.x*y;
    }
    void read()
    {
        x=Read();
        y=Read();
    }
}s,t,f[N];
struct edge
{
    point a,b;
    bool operator < (const edge &t) const
    {
        if (a==t.a) return b<t.b;
        return a<t.a;
    }
}q[N];

void slove()
{
    int now=0;
    for (int i=1;i<=m;i++)
    {
    while ((q[now+1].b-f[i])*(q[now+1].a-f[i])<0 && now<n) now++;
    while ((q[now].b-f[i])*(q[now].a-f[i])>0 && now) now--;
    ans[now]++;
    }
}

int main()
{
    while (~scanf("%d",&n) && n)
    {
    memset(ans,0,sizeof(ans));
    m=Read();
    s.read();
    t.read();
    q[0].a=s;
    q[0].b.x=s.x;
    q[0].b.y=t.y;
    for (int i=1;i<=n;i++)
        q[i].a.x=Read(),q[i].a.y=s.y,q[i].b.x=Read(),q[i].b.y=t.y;
    for (int i=1;i<=m;i++)
        f[i].read();
    sort(q+1,q+n+1);
    sort(f+1,f+m+1);
    slove();
    for (int i=0;i<=n;i++)
        printf("%d: %d\n",i,ans[i]);
    putchar('\n');
    }
    return 0;
}