[C++11][算法][穷举]输出背包问题的所有可满足解

f() {
  if (没有可以放进背包的东西) {
    输出
  } else {
    放进背包
    f()
    不放进背包
    f()
    恢复原状
  }
}

 1 #include <iostream>
 2 #include <functional>
 3 
 4 struct Pack {
 5   unsigned cnt;
 6   unsigned *w; // weights
 7   unsigned *v; // values
 8   unsigned *x; // put in or not
 9   unsigned ca; // capacity
10   
11   Pack(unsigned items_cnt) : cnt(items_cnt) {
12     w = new unsigned [items_cnt];
13     v = new unsigned [items_cnt];
14     x = new unsigned [items_cnt];
15     
16     for (int i = 0; i < items_cnt; ++i) {
17       w[i] = v[i] = x[i] = -1;
18     }
19   }
20   
21   ~Pack() {
22     delete [] w;
23     delete [] v;
24     delete [] x;
25   }
26 };
27 
28 
29 int main() {
30   unsigned c;
31  
32   std::cin >> c;
33   
34   Pack p(c);
35   
36   std::cin >> p.ca;
37   
38   for (int i = 0; i < p.cnt; ++i) {
39     std::cin >> p.w[i] >> p.v[i];
40   }
41  
42  
43  
44  
45   std::function<unsigned()> totval = [&]() {
46     unsigned cnt = 0;
47     
48     for (int i = 0; i < p.ca; ++i) {
49       if (p.x[i] == 1) cnt += p.v[i];
50     }
51     
52     return cnt;
53   };
54   
55   std::function<unsigned()> totwt = [&]() {
56     unsigned cnt = 0;
57     
58     for (int i = 0; i < p.ca; ++i) {
59       if (p.x[i] == 1) cnt += p.w[i];
60     }
61     
62     return cnt;
63   };
64   
65   std::function<void()> loop = [&]() {
66     unsigned no = -1;
67     for (int i = 0; i < p.cnt; ++i) {
68       if (p.x[i] == -1) {
69         no = i;
70         break;
71       }
72     }
73     
74     if (no == -1) {
75       std::cout << totval() << ‘ ‘;
76       for (int i = 0; i < p.cnt; ++i) {
77         std::cout << p.x[i];
78       }
79       std::cout << std::endl;
80     } else {
81       p.x[no] = 0;
82       loop();
83       
84       p.x[no] = 1;
85       
86       if (totwt() <= p.ca) {
87         loop();
88       }
89       
90       p.x[no] = -1;
91     }
92   };
93   
94   loop();
95  
96   return 0;
97 }

5
15
9 8
1 2
3 8
1 0
3 9

0 00000
9 00001
0 00010
9 00011
8 00100
17 00101
8 00110
17 00111
2 01000
11 01001
2 01010
11 01011
10 01100
19 01101
10 01110
19 01111
8 10000
17 10001
8 10010
17 10011
16 10100
25 10101
16 10110
10 11000
19 11001
10 11010
19 11011
18 11100
18 11110