POJ2728 Desert King Description David the Great has just become the king of a desert country. To win the respect of his people, he decided to build channels all over his country to bring water to every village. Villages which are connected to his cap…

题目链接:http://poj.org/problem?id=2728 Desert King Time Limit: 3000MS   Memory Limit: 65536K Total Submissions: 26878   Accepted: 7459 Description David the Great has just become the king of a desert country. To win the respect of his people, he decided…

含[最小生成树Prim]模板. Prim复杂度为$O(n^2),适用于稠密图,特别是完全图的最小生成树的求解.   Desert King Time Limit: 3000MS   Memory Limit: 65536K Total Submissions:31622   Accepted: 8670 Description David the Great has just become the king of a desert country. To win the respect of h…

http://poj.org/problem?id=2728 题目大意:求一棵生成树使得路费用和/路长之和最小(路的费用是两端点的高度差) 最小比率生成树. 我们还是01分数规划的思想将边权变为路费用-路长*枚举的答案,跑一遍最小生成树即可. 但是debug的三个小时的我要对出题人说一句. CNM无良卡常!K算法被卡正常,堆优化Prim都被卡你是什么东西????!!! #include<cstdio> #include<cmath> #include<cstring>…

题目描述: David the Great has just become the king of a desert country. To win the respect of his people, he decided to build channels all over his country to bring water to every village. Villages which are connected to his capital village will be water…

题意 n个点完全图,每个边有两个权值,求分数规划要求的东西的最小值. (n<=1000) 题解 心态炸了. 堆优化primT了. 普通的就过了. 我再也不写prim了!!!! 咳咳 最优比率生成树板子题. 公式不是很难推吧. #include<iostream> #include<cmath> #include<iomanip> #include<string.h> ; const int inf=0x7fffffff; using namespace…

这题数据量较大.普通的求MST是会超时的. d[i]=cost[i]-ans*dis[0][i] 据此二分. 但此题用Dinkelbach迭代更好 #include<cstdio> #include<cstring> #include<cmath> #include<iostream> #include<algorithm> using namespace std; #define N 1010 double mp[N][N],c[N][N],x…

一道生成树+\(0/1\)分数规划 原题链接 设每条边的距离为\(dis[x]\),两点高度差为\(h[x]\),该图的生成树为\(T\),则题目实际求的就是\(\dfrac{\sum\limits_{x\in T}h[x]}{\sum\limits_{x\in T}dis[x]}\)的最小值. 这就是经典的\(0/1\)分数规划问题. 这里我用的是二分法.二分答案,记为\(mid\).将图上的边权全部改为\(h[x]-mid\times dis[x]\),然后在上面跑最小生成树并计算边权和,如…

题目 http://poj.org/problem?id=2728 关键词:0/1分数规划,参数搜索,二分法,dinkelbach 参考资料:http://hi.baidu.com/zzningxp/item/28aa46e0fd86bdc2bbf37d03 http://hi.baidu.com/zheng6822/item/b31fbe9d5ae17536336eeb8f #include<stdio.h> #include<string.h> #include<iost…

最优比率生成树教程见http://blog.csdn.net/sdj222555/article/details/7490797 个人觉得很明白易懂,但他写的代码略囧. 模板题,但是必须Prim,不能用Kruscal,因为是完全图 Code: #include<cstdio> #include<cmath> #include<cstring> #include<algorithm> using namespace std; ]; int n; ]; ][],…