URAL1057 Amount of Degrees

 1 #include <iostream>
 2 #include <cstring>
 3 using namespace std;
 4 int x,y,k,b;
 5 int len,Bbas[51];
 6 int f[51][21][2]; //1 等于 0 小于 
 7 int solve(int p){
 8     len=0;memset(Bbas,0,sizeof(Bbas));
 9     memset(f,0,sizeof(f));
10     int t=p;
11     while (t){
12         Bbas[++len]=t%b;t=t/b;
13     }
14     if (Bbas[len]==1) {f[len][1][1]=1;f[len][0][0]=1;}
15         else {f[len][1][0]=1;f[len][0][0]=1;}
16     for (int i=len-1;i>=1;i--)
17         for (int j=0;j<=k;j++){
18             if (j==0) {
19                 f[i][j][0]=1;
20             }else {
21                 if (Bbas[i]>1) {
22                     f[i][j][0]=f[i+1][j-1][1]+f[i+1][j-1][0]+f[i+1][j][1]+f[i+1][j][0];
23                 }else {
24                     if (Bbas[i]==1) {
25                         f[i][j][0]=f[i+1][j][1]+f[i+1][j][0]+f[i+1][j-1][0];
26                         f[i][j][1]=f[i+1][j-1][1];    
27                     }
28                     if (Bbas[i]==0) {
29                         f[i][j][0]=f[i+1][j][0]+f[i+1][j-1][0];
30                         f[i][j][1]=f[i+1][j][1];
31                     }    
32                 }
33             }
34     }
35     return f[1][k][0]+f[1][k][1];
36 }
37 int main(){
38     cin>>x>>y>>k>>b;
39     cout<<solve(y)-solve(x-1)<<endl;
40     return 0;
41 }