poj1276

 1 #include <iostream>
 2 using namespace std;
 3 
 4 const int N = 10;
 5 
 6 int cash, n;
 7 int dp[100001];
 8 int D[N], m[N];
 9 
10 int main()
11 {
12     while(cin>>cash)
13     {
14         cin>>n;
15         int cnt = 0;
16         for(int i = 0; i < n; ++i)
17         {
18             cin>>m[i]>>D[i];
19         }
20 
21         memset(dp, 0, sizeof(dp));
22         dp[0] = 1;
23         for(int i = 0; i < n; ++i)
24         {
25             if(m[i] * D[i] >= cash)
26             {
27                 for(int j = D[i]; j <= cash; ++j)
28                 {
29                     dp[j] = dp[j] | dp[j-D[i]];
30                 }
31             }
32             else
33             {
34                 int k = 1;
35                 while(k < m[i])
36                 {
37                     for(int j = cash; j >= k*D[i]; --j)
38                     {
39                         dp[j] = dp[j] | dp[j-k*D[i]];
40                     }
41                     m[i] = m[i] - k;
42                     k = k * 2;
43                 }
44                 for(int j = cash; j >= D[i]*m[i]; --j)
45                 {
46                     dp[j] = dp[j] | dp[j-D[i]*m[i]];
47                 }
48             }
49         }
50 
51         for(int i = cash; i >= 0; --i)
52         {
53             if(dp[i])
54             {
55                 cout<<i<<endl;
56                 break;
57             }
58         }
59     }
60 }