[编程之美]买书问题

首先想到的是贪心算法，结果贪心策略在这里行不通- -|

贪心

 1 #include <iostream>
 2 using namespace std;
 3 
 4 int books[5];
 5 int price=8;
 6 int categorys;
 7 float consumption=0.0;
 8 float onSales5=0.25;
 9 float onSales4=0.2;
10 float onSales3=0.1;
11 float onSales2=0.05;
12 
13 int LargestCategory(int *arr,int n)
14 {
15     int cnt=0;
16     for(int i=0;i<n;++i)
17         if(arr[i]>0)
18             cnt++;
19     return cnt;
20 }
21 
22 int RemainBook(int *arr,int begin,int end)
23 {
24     for(int i=begin;i<end;++i)
25         if(books[i]>0)
26             return i;
27     return end;
28     
29 }
30 
31 int main()
32 {
33     cout <<"Enter numbers you will buy on each book:";
34     for(int i=0;i<5;++i)
35         cin >>books[i];
36 
37     while(RemainBook(books,0,5)!=5)
38     {
39         int idx=0;
40         switch(LargestCategory(books,5))
41         {
42         case 5:
43             for(int i=0;i<5;++i)
44             {
45                 idx=RemainBook(books,idx,5);
46                 books[idx]--;
47                 consumption+=(1-onSales5)*price;
48             }
49             break;
50         case 4:
51             for(int i=0;i<4;++i)
52             {
53                 idx=RemainBook(books,idx,5);
54                 books[idx]--;
55                 consumption+=(1-onSales4)*price;
56             }
57             break;
58         case 3:
59             for(int i=0;i<3;++i)
60             {
61                 idx=RemainBook(books,idx,5);
62                 books[idx]--;
63                 consumption+=(1-onSales3)*price;
64             }
65             break;
66         case 2:
67             for(int i=0;i<2;++i)
68             {
69                 idx=RemainBook(books,idx,5);
70                 books[idx]--;
71                 consumption+=(1-onSales2)*price;
72             }
73             break;
74         case 1:
75             idx=RemainBook(books,idx,5);
76             books[idx]--;
77             consumption+=price;
78             break;
79         }
80     }
81     cout <<consumption;
82     
83     return 0;
84 }