ccf 201809-4 再卖菜

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<algorithm>
 4 using namespace std;
 5 typedef long long ll;
 6 int a[300],b[300];
 7 bool vis[300][300][300];
 8 int n;
 9 bool dfs(int step)
10 {
11     if(step==n&&a[n-1]==(b[n-1]+b[n-2])/2)return 1;
12     else if(step==n)return 0;
13     if(step==0){
14         for(int i=1;;i++){
15             b[step]=i;
16             if(dfs(step+1))return 1;
17         }
18     }
19     int k=3;
20     if(step==1)k-=1;
21     for(int i=a[step-1]*k;i<a[step-1]*k+k;i++){
22         b[step]=i-b[step-1];
23         if(k==3)b[step]-=b[step-2];
24         if(vis[step][b[step-1]][b[step]])continue;
25         else vis[step][b[step-1]][b[step]]=1;
26         if(b[step]>0&&dfs(step+1))return 1;
27     }
28     return 0;
29 }
30 int main()
31 {
32     cin>>n;
33     for(int i=0;i<n;i++)scanf("%d",a+i);
34     dfs(0);
35     cout<<b[0];
36     for(int i=1;i<n;i++)printf(" %d",b[i]);
37     return 0;
38 }

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<algorithm>
 4 #include<stack>
 5 using namespace std;
 6 typedef long long ll;
 7 int a[300],b[300],k[300],i[300];
 8 bool vis[300][300][300];
 9 int n;
10 void dfs(int step=0)
11 {
12     stack<int>st;
13     st.push(step);
14     while(1){
15         step=st.top();
16         if(step==n&&a[n-1]==(b[n-1]+b[n-2])/2)return;
17         else if(step==n){
18             st.pop();
19             continue;
20         } 
21         if(step==0){
22             b[step]+=1;
23             st.push(step+1);
24             continue;
25         }
26         i[step]++;
27         if(!k[step]){
28             k[step]=3;
29             if(step==1)k[step]-=1;
30             i[step]=a[step-1]*k[step];
31         }
32         if(i[step]<a[step-1]*k[step]+k[step]){
33             b[step]=i[step]-b[step-1];
34             if(k[step]==3)b[step]-=b[step-2];
35             if(vis[step][b[step-1]][b[step]])continue;
36             else vis[step][b[step-1]][b[step]]=1;
37             if(b[step]>0)st.push(step+1);
38         }
39         else{
40             st.pop();
41             k[step]=0;
42         }
43     }
44 }
45 int main()
46 {
47     cin>>n;
48     for(int i=0;i<n;i++)scanf("%d",a+i);
49     dfs(0);
50     cout<<b[0];
51     for(int i=1;i<n;i++)printf(" %d",b[i]);
52     return 0;
53 }