我看错题了。。。都是泪啊，不存在3*4^2这种情况。。。系数必须为1。。。
1 #include <cstdio> 2 #include <cstring> 3 #include <iostream> 4 #include <vector> 5 using namespace std; 6 #define LL long long 7 int num[60]; 8 LL dp[60][60]; 9 int k,b; 10 LL dfs(int pos,int pre,int bound) 11 { 12 int i,end; 13 LL ans = 0; 14 if(pos == -1) 15 return pre == 0; 16 if(pre < 0) 17 return 0; 18 if(!bound&&dp[pos][pre] != -1) 19 return dp[pos][pre]; 20 end = bound ? num[pos]:b-1; 21 for(i = 0;i <= end;i ++) 22 { 23 if(i == 0) 24 ans += dfs(pos-1,pre,bound&&i == end); 25 else if(i == 1) 26 ans += dfs(pos-1,pre-1,bound&&i == end); 27 } 28 if(!bound) 29 dp[pos][pre] = ans; 30 return ans; 31 } 32 LL judge(LL x) 33 { 34 int pos = 0; 35 while(x) 36 { 37 num[pos++] = x%b; 38 x /= b; 39 } 40 return dfs(pos-1,k,1); 41 } 42 int main() 43 { 44 LL x,y; 45 memset(dp,-1,sizeof(dp)); 46 cin>>x>>y>>k>>b; 47 cout<<judge(y)-judge(x-1)<<endl; 48 return 0; 49 }