【动态规划】【记忆化搜索】【dfs】bzoj2748 [HAOI2012]音量调节

 1 #include<cstdio>
 2 using namespace std;
 3 int n,vis[51][1001],w[51],limit,sta;
 4 void dfs(int cur,int now)
 5 {
 6     if(cur>n) return;
 7     vis[cur][now]=1;
 8     if(now+w[cur+1]<=limit) if(!vis[cur+1][now+w[cur+1]]) dfs(cur+1,now+w[cur+1]);
 9     if(now-w[cur+1]>=0) if(!vis[cur+1][now-w[cur+1]]) dfs(cur+1,now-w[cur+1]);
10 }
11 int main()
12 {
13     scanf("%d%d%d",&n,&sta,&limit);
14     for(int i=1;i<=n;i++) scanf("%d",&w[i]);
15     dfs(0,sta);
16     for(int i=limit;i>=0;--i) if(vis[n][i])
17       {
18           printf("%d\n",i);
19           return 0;
20       }
21     puts("-1");
22     return 0;
23 }