于是求一个凸包再加上2πL就可以了。我的程序如下: #include<cstdio>#include<cstring>#include<cstdlib>#include<algorithm>#include<cmath>usingstd::sort;#defineMAXN 1002intN,L;doublesqr(doublea){returna*a; }structPoint{doublex,y;inlinePointoperator- (constPoint &t) { Point ret; ret.x=x-t...
还是那一道凸包入门题 现在用Graha-Scan算法做,更加高效: POJ 1113 Wall poj.org/problem?id=1113 #include <iostream> #include <algorithm> #include <cstdio> #include <cmath> usingnamespacestd; constdoubleeps=1e-7,Pi=3.1415926; structpoint{ intx,y; }p[1005],ans[1005]; i...
Graham Scan算法的做法是先定下一个起点,一般是最左边的点和最右边的点,然后一个个点扫过去,如果新加入的点和之前已经找到的点所构成的“壳”凸性没有变化,就继续扫,否则就把已经找到的最后一个点删去,再比较凸性,直到凸性不发生变化。分别扫描上下两个“壳”,合并在一起,凸包就找到了。这么说很抽象,我们看图...
输出要注意,如果选C++就是%.0lf,如果选G++就是%.0f,否则会WA,我也不知道为什么... 以下是本人代码: #include<cstdio>#include<cstdlib>#include<iostream>#include<algorithm>#include<cmath>#definepi 3.14159265#definee 0.00000001usingnamespacestd;intn,s[1010],top=1;doublel,ans=0;structpoint{doublex...
Learn how to implement the Graham Scan algorithm in C++ to efficiently find the convex hull of a set of points.
http:///Archive/algorithm_0109/algorithm_0109.htm 实现如下: #include <iostream> #include <math.h> using namespace std; typedef struct{double x,y;} Point; void qsortpoint(Point s[],Point base,int start,int end); void sortstartedge(Point s[],int nums); ...
凸包 凸包(Convex Hull)是一个计算几何(图形学)中的概念。点集Q的凸包是指一个最小凸多边形,满足Q中的点或者在多边形边上或者在其内。正式讨论凸包问题...
In this research a mapping system of farm land was developed and specifically this paper discusses the application of the Graham Scan algorithm to the Convex Hull method for grouping farm land. Based on the results of the system trials before and after using the convex hull, it is known that...
connect homogeneous areas of the city, either for transport system accessibility (same service frequency and same mode/service alternative) and for socio-economic aspects (same population density, income and employment, average age etc.). Graham’s scan algorithm was used to estimate the catchment ...
#include <algorithm> #include <iostream> #include <vector> #include <math.h> usingnamespacestd; //二维点(或向量)结构体定义 #ifndef _WINDEF_ structPOINT {intx;inty; }; #endif typedefvector<POINT> PTARRAY; //判断两个点(或向量)是否相等 ...