P5020 [NOIP2018 提高组] 货币系统 题解

转化为完全背包即可。

#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 25010, M = 110;

int n;
int f[N];
int a[M];

void solve() {
    int maxx = 0;
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i], maxx = max(maxx, a[i]);
    memset(f, 0, sizeof(f));
    f[0] = 1;
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        int x = a[i];
        for (int j = x; j <= maxx; j++) {
            f[j] += f[j - x];
        }
    }
    for (int i = 1; i <= n; i++) if (f[a[i]] > 1) ans++;
    cout << n - ans << '\n';
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int T;
    cin >> T;
    while (T--) solve();
    return 0;
}