1 #include<bits/stdc++.h> 2 using namespace std; 3 const int maxn=1e5+5; 4 int tot,e[40]; 5 long long c[40][40]; 6 int l,r,k,b; 7 template<class t>void red(t &x) 8 { 9 int w=1; 10 x=0; 11 char ch=getchar(); 12 while(ch>'9'||ch<'0') 13 { 14 if(ch=='-') 15 w=-1; 16 ch=getchar(); 17 } 18 while(ch>='0'&&ch<='9') 19 { 20 x=(x<<3)+(x<<1)+ch-'0'; 21 ch=getchar(); 22 } 23 x*=w; 24 } 25 void input() 26 { 27 freopen("input.txt","r",stdin); 28 } 29 void dv(int x) 30 { 31 tot=0; 32 while(x) 33 { 34 e[++tot]=x%b; 35 x/=b; 36 } 37 e[++tot]=0; 38 } 39 long long dfs(int pos,bool limit,int sum) 40 { 41 if(sum<0) 42 return 0; 43 if(pos==0) 44 return sum?0:1; 45 if(!limit&&~c[pos][sum]) 46 return c[pos][sum]; 47 int ans=0; 48 int up=limit?min(e[pos],1):1; 49 for(int i=0;i<=up;++i) 50 ans+=dfs(pos-1,limit&&(i==e[pos]),sum-i); 51 if(!limit) 52 c[pos][sum]=ans; 53 return ans; 54 } 55 long long solve(int x) 56 { 57 if(!x) 58 return 0; 59 dv(x); 60 memset(c,-1,sizeof(c)); 61 return dfs(tot,1,k); 62 } 63 void read() 64 { 65 red(l); 66 red(r); 67 red(k); 68 red(b); 69 } 70 void work() 71 { 72 printf("%lld",solve(r)-solve(l-1)); 73 } 74 int main() 75 { 76 input(); 77 read(); 78 work(); 79 return 0; 80 }
定义c[i][j]表示到第i位时还需要j个数字凑齐