dfs选取集合，dp背包判断
虽然我觉的会TLE。。
但是的确是AC了
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#define N 20001
int n, m;
int a[N];
bool vis[N], f[N];
inline int read()
{
int x = 0, f = 1;
char ch = getchar();
for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -1;
for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - '0';
return x * f;
}
inline void dp(int k)
{
int i, j;
memset(f, 0, sizeof(f));
f[0] = 1;
for(i = 1; i <= m; i++)
if(vis[i])
for(j = a[i]; j <= n; j++)
if(f[j - a[i]])
f[j] = 1;
if(!f[n]) return;
printf("%d ", k);
for(i = 1; i <= m; i++)
if(vis[i])
printf("%d ", a[i]);
exit(0);
}
inline void dfs(int cnt, int k, int last)
{
if(cnt > k)
{
dp(k);
return;
}
int i;
for(i = last + 1; i <= m; i++)
if(!vis[i])
{
vis[i] = 1;
dfs(cnt + 1, k, i);
vis[i] = 0;
}
}
int main()
{
int i;
n = read();
m = read();
for(i = 1; i <= m; i++) a[i] = read();
std::sort(a + 1, a + m + 1);
for(i = 1; i <= m; i++) dfs(1, i, 0);
return 0;
}