<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[  ]]></title><description><![CDATA[我住的城市从不下雪。]]></description><link>https://blog.youkuaiyun.com/f_cpp</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; f_cpp]]></copyright><item><title><![CDATA[POJ 1265 Area pick公式]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/41577593</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/41577593</guid><author>f_cpp</author><pubDate>Fri, 28 Nov 2014 17:10:57 +0800</pubDate><description><![CDATA[题目描述：http://poj.org/problem?id=1265
解题思路：
求一个顶点都在整数点上的多边形的面积。 题目中已经提示了多边形的面积A、多边形内的格点I与多边形边上的整点数E存在特殊的关系。然后在纸上枚举几个多边形算一算就能发现A = 0.5E + I - 1。这实际上就是pick公式。具体证明不说了。]]></description><category></category></item><item><title><![CDATA[POJ 1654 Area 有向面积]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/41577489</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/41577489</guid><author>f_cpp</author><pubDate>Fri, 28 Nov 2014 16:52:16 +0800</pubDate><description><![CDATA[题目描述：http://poj.org/problem?id=1654
解题思路：
利用叉积的性质计算三角形面积然后相加。多边形不要求一定是凸多边形，因为叉积计算出的是有向面积，带有正负号，凹下的部分会自动减去。


/*
 * 2014.11.10
 * Problem: 1654		
 * Memory: 932K			Time: 63MS
 * Language: C++		Res]]></description><category></category></item><item><title><![CDATA[POJ 3348 Cows 求凸包面积]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/41575821</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/41575821</guid><author>f_cpp</author><pubDate>Fri, 28 Nov 2014 10:36:00 +0800</pubDate><description><![CDATA[题目描述：http://poj.org/problem?id=3348
解题思路：先求凸包然后求面积。
/*
 *  2014.11.28  
 *  Problem: 3348		
 *  Memory: 180K		Time: 16MS
 *  Language: C++		Result: Accepted
 *
 */ 
#include "iostream"
#include "cma]]></description><category></category></item><item><title><![CDATA[POJ 1755 Triathlon 判断不等式有解+半平面的交]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/41378859</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/41378859</guid><author>f_cpp</author><pubDate>Sat, 22 Nov 2014 09:34:32 +0800</pubDate><description><![CDATA[题目描述：http://poj.org/problem?id=1755
解题思路：
假设一个队员的]]></description><category></category></item><item><title><![CDATA[POJ 3525 Most Distant Point from the Sea 二分+内推+半平面交]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/41280103</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/41280103</guid><author>f_cpp</author><pubDate>Wed, 19 Nov 2014 12:28:25 +0800</pubDate><description><![CDATA[题目描述：http://poj.org/problem?id=3525 


解题思路：]]></description><category></category></item><item><title><![CDATA[POJ 3335 Rotating Scoreboard 半平面的交]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/41170539</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/41170539</guid><author>f_cpp</author><pubDate>Sun, 16 Nov 2014 10:10:13 +0800</pubDate><description><![CDATA[题目描述：http://poj.org/problem?id=3335
解题思路：
把多边形的每条边看做一条直线，只有直线一侧的区域是]]></description><category></category></item><item><title><![CDATA[POJ 2653 Pick-up sticks 判断线段相交]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/41009791</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/41009791</guid><author>f_cpp</author><pubDate>Tue, 11 Nov 2014 12:30:58 +0800</pubDate><description><![CDATA[题目描述：http://poj.org/problem?id=2653


解题思路：
无非是判断线段]]></description><category></category></item><item><title><![CDATA[POJ 1556 The Doors 判断线段相交+最短路]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/41009033</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/41009033</guid><author>f_cpp</author><pubDate>Tue, 11 Nov 2014 11:28:42 +0800</pubDate><description><![CDATA[题目描述：http://poj.org/problem?id=1556]]></description><category></category></item><item><title><![CDATA[POJ 3304 Segments 枚举线段端点+判断相交]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/41008739</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/41008739</guid><author>f_cpp</author><pubDate>Tue, 11 Nov 2014 11:11:57 +0800</pubDate><description><![CDATA[所有线段在直线上的投影有公共区域，那么这条直线存在一条法线通过]]></description><category></category></item><item><title><![CDATA[POJ 1269 Intersecting Lines 判断直线相交]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/41008537</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/41008537</guid><author>f_cpp</author><pubDate>Tue, 11 Nov 2014 11:01:10 +0800</pubDate><description><![CDATA[#include "stdio.h"
#include "math.h"
#define EPS 1e-8

struct point {
	double x, y;
};
struct line {
	struct point a, b;
};

double xProduct(struct point a, struct point b) {
	return a.x*b.y - a.y*b.x]]></description><category></category></item><item><title><![CDATA[POJ 2074 Line of Sight 直线相交+线段覆盖]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/40952709</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/40952709</guid><author>f_cpp</author><pubDate>Sun, 09 Nov 2014 19:48:20 +0800</pubDate><description><![CDATA[题目描述： http://poj.org/problem?id=2074


题目大意：]]></description><category></category></item><item><title><![CDATA[POJ 2007 Scrambled Polygon 极角排序]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/40951367</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/40951367</guid><author>f_cpp</author><pubDate>Sun, 09 Nov 2014 17:25:38 +0800</pubDate><description><![CDATA[题目描述：http://poj.org/problem?id=2007]]></description><category></category></item><item><title><![CDATA[POJ 1873 The Fortified Forest  计算凸包]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/40947131</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/40947131</guid><author>f_cpp</author><pubDate>Sun, 09 Nov 2014 08:06:16 +0800</pubDate><description><![CDATA[题目描述：http://poj.org/problem?id=1873
题目大意：
一片森林中有n棵树，现在需要砍掉其中的一些树做成围栏把剩下的树围起来。给定每棵树的(x,y)坐标、价值和砍掉之后能做成围栏的长度。找到最优的一种可行方案使得砍掉的树的价值最小。如果两种方案砍掉树的价值相同，则选择砍掉数目数量少的哪一个方案。
多组数据，2 
解题思路：
看到n的范围马上想到枚举。枚举每棵树]]></description><category></category></item><item><title><![CDATA[POJ 1228 Grandpa's Estate 计算凸包+判断点在线段上]]></title><link>https://blog.youkuaiyun.com/f_cpp/article/details/40927767</link><guid>https://blog.youkuaiyun.com/f_cpp/article/details/40927767</guid><author>f_cpp</author><pubDate>Sat, 08 Nov 2014 21:43:21 +0800</pubDate><description><![CDATA[题目链接：http://poj.org/problem?id=1228]]></description><category></category></item></channel></rss>