[SCOI2009]windy数

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<algorithm>
 5 #include<cmath>
 6 using namespace std;
 7 int f[21][11],s[21];
 8 int dfs(int pos,int pre,int k,int flag)
 9 {int i;
10   if (pos==0) return 1;
11   if (k&&!flag&&f[pos][pre]!=-1) return f[pos][pre];
12   int ed=9,cnt=0;
13   if (flag) ed=s[pos];
14   for (i=0;i<=ed;i++)
15     if (pre==-1||abs(i-pre)>=2)
16     {
17       if (k==0&&i==0) cnt+=dfs(pos-1,-1,0,flag&&(i==ed));
18       else
19       cnt+=dfs(pos-1,i,k|(i!=0),flag&&(i==ed));
20     }
21   if (!flag&&k) f[pos][pre]=cnt;
22   return cnt;
23 }
24 int solve(int x)
25 {
26   memset(f,-1,sizeof(f));
27   int len=0;
28   if (x==0) return 1;
29   while (x)
30     {
31       s[++len]=x%10;
32       x/=10;
33     }  
34   return dfs(len,-1,0,1);
35 }
36 int main()
37 {int A,B;
38   cin>>A>>B;
39   printf("%d",solve(B)-solve(A-1));
40 }