题目传送门 题意:POJ 2318 有一个长方形,用线段划分若干区域,给若干个点,问每个区域点的分布情况 分析:点和线段的位置判断可以用叉积判断.给的线段是排好序的,但是点是无序的,所以可以用二分优化.用到了叉积 /************************************************ * Author :Running_Time * Created Time :2015/10/23 星期五 11:38:18 * File Name :POJ_2318.cpp ****…

POJ 2318: 题目大意:给定一个盒子的左上角和右下角坐标,然后给n条线,可以将盒子分成n+1个部分,再给m个点,问每个区域内有多少各点 这个题用到关键的一步就是向量的叉积,假设一个点m在 由abcd围成的四边形区域内,那么向量ab, bc, cd, da和点的关系就是,点都在他们的同一侧,我是按照逆时针来算的,所以只需要判断叉积是否小于0就行了.还有一个问题就是这个题要求时间是2s,所以直接找,不用二分也能过,不过超过1s了,最好还是二分来做,二分时间170ms,二分的时候要把最左边的一条…

2318 TOYS 2398 Toy Storage 题意 : 给你n块板的坐标,m个玩具的具体坐标,2318中板是有序的,而2398无序需要自己排序,2318要求输出的是每个区间内的玩具数,而2318要求输出的是有 i 个玩具的区间有几个. 思路 : 两个题基本差不多,只不过2398排一下序,然后再找个数组标记一下就行. 这个题我一开始没想到用二分,判断了点在四边形内但是没写下去,然后看了网上的二分区间,利用叉积判断点在左边还是右边. 2318代码: #include <stdio.h> #…

计算几何终于开坑了... 叉积+二分. #include<iostream> #include<cstdio> #include<cstring> #include<algorithm> #define maxn 5050 using namespace std; struct point { int x,y; point (int x,int y):x(x),y(y) {} point () {} friend point operator-(point…

题目传送门:POJ 2318 TOYS Description Calculate the number of toys that land in each bin of a partitioned toy box. Mom and dad have a problem - their child John never puts his toys away when he is finished playing with them. They gave John a rectangular bo…

题目传送门:poj 2398 Toy Storage 题目大意:一个长方形的箱子,里面有一些隔板,每一个隔板都可以纵切这个箱子.隔板将这个箱子分成了一些隔间.向其中扔一些玩具,每个玩具有一个坐标,求有\(t​\)个玩具的隔间数(对\(t>0​\)都要输出). 题目分析:涉及到计算几何的知识是求点在线的哪一侧.可以利用叉积来做.取点\(A\)到隔板的上端点\(B\)的向量\(\vec{AB}\)叉乘点\(A\)到隔板的下端点\(C\)的向量\(\vec{AC}\).叉积的公式\(\vec a\ti…

TOYS Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 10666   Accepted: 5128 Description Calculate the number of toys that land in each bin of a partitioned toy box.  Mom and dad have a problem - their child John never puts his toys away…

Toy Storage Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 5439   Accepted: 3234 Description Mom and dad have a problem: their child, Reza, never puts his toys away when he is finished playing with them. They gave Reza a rectangular box…

Toy Storage Time Limit: 1000MS Memory Limit: 65536K Description Mom and dad have a problem: their child, Reza, never puts his toys away when he is finished playing with them. They gave Reza a rectangular box to put his toys in. Unfortunately, Reza is…

<题目链接> 题目大意: 给出矩形4个点和n个挡板俩顶点的位置,这n个挡板将该矩形分成 n+1块区域,再给你m个点的坐标,然你输出每个区域内有几个点. 解题思路: 用叉乘即可简单判断点与直线的位置关系,对每一个点,遍历挡板,直到找到符合的区间为止. #include <cstdio> #include <iostream> #include <algorithm> #include <cstring> using namespace std; +…