寒假第七周 2.22 --- 2.28

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<iostream>
 4 #include<algorithm>
 5 #include<vector>
 6 using namespace std;
 7 
 8 const int mod = 1e9+7;
 9 typedef long long LL;
10 const int maxn = 2005;
11 LL dp[maxn][maxn][2];
12 int m,d,n,f[maxn][maxn];
13 char s[maxn],p[maxn];
14 
15 LL solve(char* t){
16     memset(dp,0,sizeof(dp));
17         int v = t[1]-‘0‘;
18         for(int i = 1;i <= t[1]-‘0‘;i++){
19             if(i == d) continue;
20             if(i == v) dp[1][v%m][1] += 1LL;
21             else dp[1][i%m][0] += 1LL;
22       //      printf("dp[1][%d][0] = %d dp[1][%d][1] = %d\n",i%2,dp[1][i%m][0],i%2,dp[1][i%m][1]);
23         }
24 
25         for(int i = 2;i <= n;i++){
26             for(int j = 0;j < m;j++){
27                 if(i%2){
28                     for(int k = 0;k <= 9;k++){
29                         if(k == d) continue;
30                         dp[i][(j*10+k)%m][0] += dp[i-1][j][0];
31                         if(k == t[i]-‘0‘) dp[i][(j*10+k)%m][1] += dp[i-1][j][1];
32                         if(k < t[i]-‘0‘) dp[i][(j*10+k)%m][0] += dp[i-1][j][1];
33                     }
34                 }
35                 else{
36                     dp[i][(j*10+d)%m][0] += dp[i-1][j][0];
37                     if(d == t[i]-‘0‘) dp[i][(j*10+d)%m][1] += dp[i-1][j][1];
38                     if(d < t[i]-‘0‘) dp[i][(j*10+d)%m][0] += dp[i-1][j][1];
39                 }
40                 dp[i][j][0] %= mod;
41                 dp[i][j][1] %= mod;
42              //   printf(">_<dp[%d][%d][0] = %d  ",i,j,dp[i][j][0]);
43                // printf("dp[%d][%d][1] = %d\n",i,j,dp[i][j][0]);
44             }
45         }
46      //   printf("dp[%d][0][0] = %d",n,dp[n][0][0]);
47        // printf(" dp[%d][0][1] = %d\n",n,dp[n][0][1]);
48         return (dp[n][0][0]+dp[n][0][1])%mod;
49 }
50 
51 int ok(char* s){
52     for(int i = 1;i <= n;i++){
53         if(i%2 == 1 && (s[i]-‘0‘) == d) return 0;
54         if(i%2 == 0 && (s[i]-‘0‘) != d) return 0;
55     }
56     LL res = 0;
57     for(int i = 1;i <= n;i++){
58         res = (res*10+(s[i]-‘0‘))%m;
59     }
60     if(res == 0) return 1;
61     return 0;
62 }
63 
64 int main(){
65     while(scanf("%d %d",&m,&d) != EOF){
66         scanf("%s",s+1);
67         scanf("%s",p+1);
68         n = strlen(s+1);
69             LL l = solve(s);
70             LL r = solve(p);
71             LL ans = (r-l+mod)%mod;
72             if(ok(s)) ans++;
73             printf("%I64d\n",ans);
74     }
75     return 0;
76 }