[IDDFS+背包] 洛谷P2744 [USACO5.3]量取牛奶Milk Measuring

#include <cstdio>
#include <algorithm>
#include <cstring>

int q,n,bucket[105];
int v[105];
int limit;
bool dp[23333];
bool vis[122];

bool Can(){
    memset(dp,0,sizeof(dp));
    dp[0] = 1;
    for(int i=1;i<=limit;i++){
        for(int j=v[i];j<=q;j++){
            dp[j]+=dp[j-v[i]];
        }
    }
    if(dp[q]) return true;
    return false;
}

void dfs(int pos){
    if(pos > limit ){
        if( Can() ){
            printf("%d\n",limit);
            for(int i=1;i<=limit;i++) printf("%d ",v[i]);
            exit(0);
        }
        return;
    }
    for(int i=1;i<=n;i++){
        if( !vis[i] ){
            vis[i] = 1;
            v[pos] = bucket[i];
            dfs(pos+1);
            vis[i] = 0;
        }
    }
}

int main(){
    scanf("%d",&q);
    scanf("%d",&n);
    for(int i=1;i<=n;i++) scanf("%d",&bucket[i]);
    std::sort(bucket+1,bucket+1+n);
    for(int i=1;i<=n;i++){
        limit = i;
        dfs(1);
    }
    return 0;
}