POJ 2318 TOYS 二分+叉积

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
#include <cstdlib>
#include <cmath>
#include <map>
#include <sstream>
#include <queue>
#include <vector>
#define MAXN 100001
#define MAXM 211111
#define eps 1e-8
#define INF 500000001
using namespace std;
int dblcmp(double d)
{
if(fabs(d) < eps) return 0;
return d > eps ? 1 : -1;
}
struct point
{
double x, y;
point(){}
point(double _x, double _y):
x(_x), y(_y) {};
void input()
{
scanf("%lf%lf", &x, &y);
}
void output()
{
printf("%.2f %.2f\n", x, y);
}
double det(point p)
{
return x * p.y - y * p.x;
}
point sub(point p)
{
return point(x - p.x, y - p.y);
}
}up[5555], down[5555];
double getcross(point a, point o, point b)
{
a = a.sub(o);
b = b.sub(o);
return a.det(b);
}
int num[5555];
int n, m;
int main()
{
double xa, xb, ya, yb, ui, li;
int cas = 0;
while(scanf("%d", &n) != EOF && n)
{
scanf("%d%lf%lf%lf%lf", &m, &xa, &ya, &xb, &yb);
if(cas++) puts("");
up[0] = point(xa, ya);
down[0] = point(xa, yb);
for(int i = 1; i <= n; i++)
{
scanf("%lf%lf", &ui, &li);
up[i] = point(ui, ya);
down[i] = point(li, yb);
}
up[n + 1] = point(xb, ya);
down[n + 1] = point(xb, yb);
memset(num, 0, sizeof(num));
point tmp;
for(int i = 0; i < m; i++)
{
tmp.input();
int low = 0, high = n + 1;
while(low <= high)
{
int mid = (low + high) >> 1;
if(dblcmp(getcross(up[mid], tmp, down[mid])) > 0)
low = mid + 1;
else high = mid - 1;
}
num[low - 1] ++;
}
for(int i = 0; i <= n; i++) printf("%d: %d\n", i, num[i]);
}
return 0;
}