bzoj 1026[SCOI2009]windy数 - 数位dp

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <algorithm> 
 5 #define LL long long
 6 
 7 using namespace std;
 8 
 9 int tot = 0;
10 int A, B;
11 int d[15];
12 int f[20][20];
13 inline LL read()
14 {
15     LL x = 0, w = 1; char ch = 0;
16     while(ch <‘0‘ || ch > ‘9‘) {
17         if(ch == ‘-‘) {
18             w = -1;
19         }
20         ch = getchar();
21     }
22     while(ch >= ‘0‘ && ch <= ‘9‘)  {
23         x = x * 10 + ch - ‘0‘;
24         ch = getchar();
25     }
26     return x * w;
27 }
28 
29 void init()
30 {
31     f[0][0] = 1;
32     for(int i = 1; i <= 10; i++) {
33         for(int j = 0; j <= 9; j++) {
34             for(int k = 0; k <= 9; k++) {
35                 if(abs(j - k) >= 2 || i == 1) {
36                     f[i][j] += f[i - 1][k];
37                 }
38             }
39         }
40     }
41 }
42 
43 LL cal(int num)
44 {
45     int ans = 0;
46     tot = 0;
47     while(num) {
48         d[++tot] = num % 10;
49         num = num / 10;
50     }
51     d[tot + 1] = 1e5;
52     for(int i = tot; i >= 1; i--) {
53         if(i == tot) {
54             for(int j = 1; j < d[i]; j++) {
55                 ans += f[i][j];
56             }
57         } else {
58             if(abs(d[i + 1] - d[i + 2]) < 2) {
59                 break;
60             }
61             for(int j = 0; j < d[i]; j++) {
62                 if(abs(d[i + 1] - j) >= 2) {
63                     ans += f[i][j];
64                 }
65             }
66         }
67     }
68 //    cout<<ans<<endl;
69     for(int i = tot - 1; i >= 1; i--) {
70         for(int j = 1; j <= 9; j++) {
71             ans += f[i][j];    
72         }
73     }
74     return ans;
75 }
76 int main()
77 {
78     init();
79     A = read(), B = read();
80 //    cout<<cal(A)<<endl;
81     printf("%d\n", cal(B + 1) - cal(A));
82     return 0;
83 }