POJ 3111 K Best（01分数规划）

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POJ - 3111 K Best 0-1分数规划二分

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…

POJ 2976 Dropping tests 01分数规划

给出n(n<=1000)个考试的成绩ai和满分bi,要求去掉k个考试成绩,使得剩下的∑ai/∑bi*100最大并输出. 典型的01分数规划要使∑ai/∑bi最大,不妨设ans=∑ai/∑bi,则∑ai-ans*∑bi=0. 设f[ans]=∑ai-ans*∑bi,我们要求一个ans的最大值,使得存在一组解,满足f[ans]=0,而其他的任意解都有f[ans]<=0(如果f[ans]>0,说明∑ai/∑bi>ans,即还有比ans更优的解),对于∑ai/∑bi,从0~1二分枚举答案…

POJ 2976 Dropping tests 01分数规划模板

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…

POJ 2728 Desert King (01分数规划）

Desert King Time Limit: 3000MS Memory Limit: 65536K Total Submissions:29775 Accepted: 8192 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…

$POJ$2976 $Dropping\ tests$ 01分数规划+贪心

正解:01分数规划解题报告: 传送门! 板子题鸭,,, 显然考虑变成$a[i]-mid\cdot b[i]$,显然无脑贪心下得选出最大的$k$个然后判断是否大于0就好(,,,这么弱智真的算贪心嘛$TT$ 然后就做完辣,,, 我真的$jio$得我做的题越来越水了是为什么,,,啊难过,越来越菜了可海星$TT$ #include<algorithm> #include<iomanip> #include<cstdio> using namespace std; #defin…

POJ - 2976 Dropping tests(01分数规划---二分(最大化平均值))

题意:有n组ai和bi,要求去掉k组,使下式值最大. 分析: 1.此题是典型的01分数规划. 01分数规划:给定两个数组,a[i]表示选取i的可以得到的价值,b[i]表示选取i的代价.x[i]=1代表选取i,否则x[i]=0. 求一个选择方案使得所有选择物品的总收益/总代价的值最大或是最小. 即y=Σ(a[i]*x[i])/Σ(b[i]*x[i])取得最值. 2.这类问题可以用二分解决. 最大化平均值: 设某种选取方案后得到的值为Σa[i]/Σb[i],判断此时二分到的值mid是否符合要求,若Σ…