CF10E Greedy Change 判断硬币系统是否能用贪心策略

 1 #include <map>
 2 #include <set>
 3 #include <cmath>
 4 #include <queue>
 5 #include <stack>
 6 #include <cstdio>
 7 #include <string>
 8 #include <vector>
 9 #include <cstring>
10 #include <iostream>
11 #include <algorithm>
12 #define ll long long
13 #define pii pair<int, int>
14 #define mp(x,y) make_pair(x,y)
15 using namespace std;
16 const int inf = 0x7fffffff;
17 const double eps = 1e-12;
18 const int mod = 1e9+7;
19 const int maxn = 300005;
20 using namespace std;
21 int c[401];
22 int main() {
23     int n;
24     cin>>n;
25     for (int i=0; i<n; i++)
26         cin>>c[i];
27     int ans=-1;
28     for (int i=1; i<n; i++) {
29         for (int j=i; j<n; j++) {
30             //calculate G(c[i-1]-1) and w
31             int p=c[i-1]-1, cnt=1, w=c[j];
32             for (int k=i; k<=j; k++) {
33                 cnt+=p/c[k];
34                 w+=p/c[k]*c[k];
35                 p%=c[k];
36             }
37             p=w;
38             //judge whether M(w)<G(w)
39             for (int k=0; k<n; k++) {
40                 cnt-=p/c[k];
41                 p%=c[k];
42             }
43             if (cnt<0&&(ans==-1||w<ans))
44                 ans=w;
45         }
46     }
47     cout << ans << endl;
48     return 0;
49 }