洛谷 P1474 货币系统 Money Systems

题目传送门

解题思路:

一个披着外壳的完全背包.

AC代码:

#include<iostream>
#include<cstdio>

using namespace std;

long long v,n,a[30],f[10001]; 

int main() {
    scanf("%lld%lld",&n,&v);
    for(int i = 1;i <= n; i++)
        scanf("%lld",&a[i]);
    f[0] = 1;
    for(int i = 1;i <= n; i++)
        for(int j = a[i];j <= v; j++)
            f[j] += f[j - a[i]];
    printf("%lld",f[v]);
    return 0;
}