ural 1057. Amount of Degrees 数位dp

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 #define pb(x) push_back(x)
 4 #define ll long long
 5 #define mk(x, y) make_pair(x, y)
 6 #define lson l, m, rt<<1
 7 #define mem(a) memset(a, 0, sizeof(a))
 8 #define rson m+1, r, rt<<1|1
 9 #define mem1(a) memset(a, -1, sizeof(a))
10 #define mem2(a) memset(a, 0x3f, sizeof(a))
11 #define rep(i, a, n) for(int i = a; i<n; i++)
12 #define ull unsigned long long
13 typedef pair<int, int> pll;
14 const double PI = acos(-1.0);
15 const double eps = 1e-8;
16 const int mod = 1e9+7;
17 const int inf = 1061109567;
18 const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
19 int digit[35];
20 int dp[35][30], b, k;
21 int dfs(int len, int num, int fp) {
22     if(!len) {
23         return num == k;
24     }
25     if(!fp&&dp[len][num]!=-1) {
26         return dp[len][num];
27     }
28     int maxx = fp?digit[len]:b-1, ret = 0;
29     for(int i = 0; i<=maxx&&i<=1; i++) {
30         ret += dfs(len-1, num+i, i==maxx&&fp);
31     }
32     if(!fp)
33         return dp[len][num] = ret;
34     return ret;
35 }
36 int cal(int n) {
37     int len = 0;
38     while(n) {
39         digit[++len] = n%b;
40         n/=b;
41     }
42     return dfs(len, 0, 1);
43 }
44 int main()
45 {
46     int A, B;
47     while(cin>>A>>B>>k>>b) {
48         mem1(dp);
49         printf("%d\n", cal(B)-cal(A-1));
50     }
51     return 0;
52 }