URAL 1057. Amount of Degrees(数位DP)

题目链接

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 }