解题思路

代码

原始做法

#include <iostream>

using namespace std;

const int N = 10010, M = 110;
int f[N][N], a[M];

int main() {
    int n, m;
    cin >> n >> m;
    for (int i = 1; i <= n; i++) cin >> a[i];

    f[0][0] = 1;
    for (int i = 1; i <= n; i++) {
        f[i][0] = 1;
        for (int j = 1; j <= m; j++) {
            f[i][j] = f[i - 1][j];
            if (j >= a[i]) f[i][j] += f[i - 1][j - a[i]];
        }
    }
    cout << f[n][m] << endl;

    return 0;
}

优化空间

#include <iostream>

using namespace std;

const int N = 10010, M = 110;
int f[N], a[M];

int main() {
    int n, m;
    cin >> n >> m;
    for (int i = 1; i <= n; i++) cin >> a[i];

    f[0] = 1;
    for (int i = 1; i <= n; i++) {
        for (int j = m; j >= a[i]; j--) f[j] += f[j - a[i]];
    }
    cout << f[m] << endl;

    return 0;
}