洛谷 P2725 邮票 Stamps

题目传送门

解题思路:

f[i]表示凑总面值i所需的最少邮票张数,然后快乐的跑完全背包.

AC代码:

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<map>
 4 #include<cstring>
 5 
 6 using namespace std;
 7 
 8 int k,n,a[51],aa,now,f[2000001];
 9 map<int,bool> vis;
10 
11 int main() {
12     scanf("%d%d",&k,&n);
13     for(int i = 1;i <= n; i++) {
14         scanf("%d",&a[i]);
15         aa = max(aa,a[i]);
16     }
17     memset(f,0x3f3f3f,sizeof(f));
18     f[0] = 0;
19     for(int i = 1;i <= n; i++) f[a[i]] = 1;
20     for(int i = 1;i <= n; i++)
21         for(int j = a[i];j <= aa * k; j++)
22             f[j] = min(f[j],f[j-a[i]] + 1);
23     for(int i = 1;i <= aa * k; i++)
24         if(f[i] > k) {
25             printf("%d",i - 1);
26             return 0;
27         }
28     printf("%d",k * aa);
29     return 0;
30 }