HDU 4968 简单dp背包问题

最新推荐文章于 2021-08-09 16:42:12 发布

等我学会后缀自动机

最新推荐文章于 2021-08-09 16:42:12 发布

阅读量175

点赞数

CC 4.0 BY-SA版权

分类专栏： HDU习题集

本文链接：https://blog.youkuaiyun.com/qq_37451344/article/details/80099199

HDU习题集专栏收录该内容

259 篇文章

订阅专栏

本文介绍了一个算法问题，旨在通过计算不同课程得分来确定学生平均绩点（GPA）的可能范围。具体而言，该算法考虑了成绩转换为4分制绩点的方法，并计算在给定平均分和课程数量的情况下，可能的最低和最高GPA值。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Improving the GPA

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 131072/131072 K (Java/Others)
Total Submission(s): 820 Accepted Submission(s): 586

Problem Description

Xueba: Using the 4-Point Scale, my GPA is 4.0.

In fact, the AVERAGE SCORE of Xueba is calculated by the following formula:
AVERAGE SCORE = ∑(Wi * SCOREi) / ∑(Wi) 1<=i<=N
where SCOREi represents the scores of the ith course and Wi represents the credit of the corresponding course.

To simplify the problem, we assume that the credit of each course is 1. In this way, the AVERAGE SCORE is ∑(SCOREi) / N. In addition, SCOREi are all integers between 60 and 100, and we guarantee that ∑(SCOREi) can be divided by N.

In SYSU, the university usually uses the AVERAGE SCORE as the standard to represent the students’ level. However, when the students want to study further in foreign countries, other universities will use the 4-Point Scale to represent the students’ level. There are 2 ways of transforming each score to 4-Point Scale. Here is one of them.

The student’s average GPA in the 4-Point Scale is calculated as follows: GPA = ∑(GPAi) / N
So given one student’s AVERAGE SCORE and the number of the courses, there are many different possible values in the 4-Point Scale. Please calculate the minimum and maximum value of the GPA in the 4-Point Scale.

Input

The input begins with a line containing an integer T (1 < T < 500), which denotes the number of test cases. The next T lines each contain two integers AVGSCORE, N (60 <= AVGSCORE <= 100, 1 <= N <= 10).

Output

For each test case, you should display the minimum and maximum value of the GPA in the 4-Point Scale in one line, accurate up to 4 decimal places. There is a space between two values.

Sample Input

  475 175 275 375 10
 

Sample Output

  3.0000 3.00002.7500 3.00002.6667 3.16672.4000 3.2000
  
    Hint
   
In the third case, there are many possible ways to calculate the minimum value of the GPA in the 4-Point Scale.For example, Scores 78 74 73 GPA = (3.0 + 2.5 + 2.5) / 3 = 2.6667Scores 79 78 68 GPA = (3.0 + 3.0 + 2.0) / 3 = 2.6667Scores 84 74 67 GPA = (3.5 + 2.5 + 2.0) / 3 = 2.6667Scores 100 64 61 GPA = (4.0 + 2.0 + 2.0) / 3 = 2.6667

Author

SYSU

Source

2014 Multi-University Training Contest 9

Recommend

We have carefully selected several similar problems for you: 6275 6274 6273 6272 6271

注意点：根据题目规定分数必须是六十分及以上，所以在状态初始化时要注意。

#include<iostream>
#include<queue>
#include<stdio.h>
#include<cstring>
#include<cmath>
using namespace std;
typedef long long LL;
#define maxn 10000000
int AVG,N,sum;
double dp[11][1005],tmp[11][1005];
double mp[101];
double lans,uans;
int main()
{
    for(int i=0;i<101;i++)
    {
        if(i<60) mp[i]=-1000;//
        if(i>=60&&i<70) mp[i]=2.0;
        if(i>=70&&i<75) mp[i]=2.5;
        if(i>=75&&i<80) mp[i]=3.0;
        if(i>=80&&i<85) mp[i]=3.5;
        if(i>=85) mp[i]=4.0;
    }
    int t;cin>>t;
    while(t--)
    {
        cin>>AVG>>N;
        sum=AVG*N;
        for(int i=0;i<=100;i++)  dp[1][i]=tmp[1][i]=mp[i];
        for(int i=2;i<=N;i++)
            for(int j=(i-1)*60+1;j<=sum;j++)
        {
            dp[i][j]=10000;
            tmp[i][j]=-1;
            for(int k=60;k<=100;k++)
            {
                if(dp[i-1][j-k]> 0) dp[i][j]=min(dp[i][j],dp[i-1][j-k]+mp[k]);
                 if(tmp[i-1][j-k]> 0) tmp[i][j]=max(tmp[i][j],tmp[i-1][j-k]+mp[k]);
            }
        }
        lans=dp[N][sum]/N;
        uans=tmp[N][sum]/N;
        printf("%.4f %.4f\n",lans,uans);
    }
    return 0;
}