题目链接:http://poj.org/problem?id=3111 K Best Time Limit: 8000MS   Memory Limit: 65536K Total Submissions: 11380   Accepted: 2935 Case Time Limit: 2000MS   Special Judge Description Demy has n jewels. Each of her jewels has some value vi and weight wi.…

K Best Time Limit: 8000MS   Memory Limit: 65536K Total Submissions: 12812   Accepted: 3290 Case Time Limit: 2000MS   Special Judge Description Demy has n jewels. Each of her jewels has some value vi and weight wi. Since her husband John got broke aft…

题目链接:http://poj.org/problem?id=3111 求选k对数,使得上述式子值最大.容易想到设左边为一个值,对式子变形以下,得到sigma(v-r*w))==0的时候就是最大的,<0是最小的.二分这个r就行了. #include <algorithm> #include <iostream> #include <iomanip> #include <cstring> #include <climits> #include…

题目链接:http://poj.org/problem?id=2976 Dropping tests Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 13615   Accepted: 4780 Description In a certain course, you take n tests. If you get ai out of bi questions correct on test i, your cumula…

链接 前置技能 二分思想 最短路算法 一些数学脑细胞? 问题模型1基本01分数规划问题给定n个二元组(valuei,costi),valuei是选择此二元组获得的价值(非负),costi是选择此二元组付出的代价(非负),设xi(xi∈{0,1}代表第ii个二元组的选与不选,最大(小)化下式 下面先说最大化 解决方法 二分法 设r最大值为r∗,…

因为搜索关于CFRound277.5E题的题解时发现了这篇文章,很多地方都有值得借鉴的东西,因此转了过来 原文:http://www.cnblogs.com/perseawe/archive/2012/05/03/01fsgh.html [关键字] 0/1分数规划.最优比率生成树.最优比率环 [背景] 根据楼教主的回忆录,他曾经在某一场比赛中秒掉了一道最优比率生成树问题,导致很多人跟风失败,最终悲剧. 自己总结了一些这种问题的解法,因为水平有限,如果有错误或是麻烦的地方,尽管喷,邮箱或是下方留言…

Dropping tests   Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 6373   Accepted: 2198 [Description] In a certain course, you take n tests. If you get ai out of bi questions correct on test i, your cumulative average is defined to be . G…

Desert King Time Limit: 3000MS   Memory Limit: 65536K Total Submissions:33847   Accepted: 9208 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 count…

P.S.又是一个抽时间学了2个小时的新东西......讲解在上半部分,题解在下半部分. 先说一下转的原文:http://www.cnblogs.com/perseawe/archive/2012/05/03/01fsgh.html我挑选部分转了过来:01分数规划问题 定义:给定两个数组,a[i]表示选取i的收益,b[i]表示选取i的代价.如果选取i,定义x[i]=1否则x[i]=0.每一个物品只有选或者不选两种方案,求一个选择方案使得R=sigma(a[i]*x[i])/sigma(b[i]*x…

Sightseeing Cows Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 9703   Accepted: 3299 Description Farmer John has decided to reward his cows for their hard work by taking them on a tour of the big city! The cows must decide how best to…