POJ 2398 Toy Storage （叉积+二分）

题意：有一个长方形盒子，有n个板隔开，分成n+1个区域，又给了m个玩具的坐标，问你 $i(0<i\le m)$个玩具的区域有多少个。

题解：叉积+二分
跟这题思路一样，不过隔板的输入顺序是打乱的，要排一下序，输出格式也不同。

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<algorithm>
#include<queue>
#include<stack>
#include<cmath>
#include<vector>
#include<fstream>
#include<set>
#include<map>
#include<sstream>
#include<iomanip>
#define ll long long
using namespace std;
struct node {
	int xup, xdo;
	node(){}
	node(int x, int y) :xup(x), xdo(y) {}
}point[1010];
bool cmp(node& a, node& b) {
	return a.xup < b.xup;
}
int n, m, xa, ya, xb, yb, x, y;
int pos[1010], cnt[1010];
bool check(int x, int y, int id) {
	int temp = (point[id].xup - x) * (yb - y) - (point[id].xdo - x) * (ya - y);
	if (temp < 0) return true;
	else return false;
}
int main() {
	while (~scanf("%d", &n) && n) {
		memset(pos, 0, sizeof(pos));
		memset(cnt, 0, sizeof(cnt));
		scanf("%d%d%d%d%d", &m, &xa, &ya, &xb, &yb);
		for (int i = 0; i < n; i++) {
			scanf("%d%d", &x, &y);
			point[i] = node(x, y);
		}
		sort(point, point + n, cmp);
		for (int i = 0; i < m; i++) {
			scanf("%d%d", &x, &y);
			int l = 0, r = n - 1, mid;
			while (l <= r) {
				int mid = (l + r) >> 1;
				if (check(x, y, mid)) r = mid - 1;
				else l = mid + 1;
			}
			pos[l]++;
		}
		for (int i = 0; i <= n; i++) {
			cnt[pos[i]]++;
		}
		puts("Box");
		for (int i = 1; i <= m; i++) {
			if (cnt[i] == 0) continue;
			printf("%d: %d\n", i, cnt[i]);
		}
	}
	return 0;
}