BZOJ1088 扫雷

水题，模拟。对于最后的方案数最多只会是2，想好久，又睡了一觉才想到这个，剩下的就好办了

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <vector>
 4 #include <cmath>
 5 #include <algorithm>
 6 using namespace std;
 7 #define lson l,m,rt<<1
 8 #define rson m+1,r,rt<<1|1
 9 const int maxn = 10005;
10 int a[maxn],vis[maxn];
11 int n;
12 bool ok()
13 {
14     for(int i = 2;i<n;++i){
15         if(a[i]==1){
16             if(vis[i]==1&&vis[i-1]==1)return false;
17             if(vis[i]==1||vis[i-1]==1)vis[i+1] = 0;
18             else vis[i+1] = 1;
19         }
20         else if(a[i]==2){
21             if(vis[i]==0&&vis[i-1]==0)return false;
22             if((vis[i]==1&&vis[i-1]==0)||(vis[i]==0&&vis[i-1]==1))vis[i+1] = 1;
23             else vis[i+1] = 0;
24         }
25         else if(a[i]==3){
26             if(!(vis[i]==1&&vis[i-1]==1))return false;
27             vis[i+1] = 1;
28         }
29         else if(a[i]==0){
30             if(vis[i]||vis[i-1])return false;
31             vis[i+1] = 0;
32         }
33         else return false;
34     }
35     if(vis[n-1]+vis[n]==a[n])return true;
36     else return false;
37 }
38 int main()
39 {
40     //freopen("in.txt","r",stdin);
41     scanf("%d",&n);
42     for(int i = 1;i<=n;++i)scanf("%d",&a[i]);
43     if(n==1){
44         if(a[1]==1||a[1]==0)printf("1\n");
45         else printf("0\n");
46         return 0;
47     }
48     if(a[1]==3){printf("0\n");return 0;}
49     memset(vis,-1,sizeof(vis));
50     int ans = 0;
51     if(a[1]==2){
52         vis[1] = vis[2] = 1;
53         if(ok())ans++;
54     }
55     else if(a[1]==0){
56         vis[1] = vis[2] = 0;
57         if(ok())ans++;
58     }
59     else if(a[1]==1){
60         vis[1] = 1;vis[2] = 0;
61         if(ok())ans++;
62         memset(vis,-1,sizeof(vis));
63         vis[1] = 0;vis[2] = 1;
64         if(ok())ans++;
65     }
66     printf("%d\n",ans);
67     return 0;
68 }