A - Beautiful numbers

Posted 2020-11-10 jaydenouyang

 1     #include <iostream>
 2     #include <algorithm>
 3     #include <cstring>
 4     #include <cstdio>
 5     #include <cstdlib>
 6     #include <vector>
 7 
 8     using namespace std;
 9 
10     #define LL long long
11     const int MOD = 2520;
12     LL dp[20][50][2550];
13     int a[20];
14     int Hash[2550];
15 
16     LL gcd(LL a, LL b)
17     {
18         return b?gcd(b,a%b):a;
19     }
20 
21     LL dfs(int pos, int num, int lcm, bool limit)
22     {
23         if(-1==pos) return num%lcm == 0;
24         if(!limit && ~dp[pos][Hash[lcm]][num]) return dp[pos][Hash[lcm]][num];
25         LL ans = 0;
26         int end = limit?a[pos]:9;
27         for(int i=0; i<=end; i++)
28             ans += dfs(pos-1, (num*10+i)%MOD, i?lcm*i/gcd(lcm,i):lcm, limit&&i==a[pos]);
29         if(!limit) dp[pos][Hash[lcm]][num] = ans;
30         return ans;
31     }
32 
33     LL solve(LL n)
34     {
35         int pos = 0;
36         while(n)
37         {
38             a[pos++] = n%10;
39             n /= 10;
40         }
41         return dfs(pos-1, 0, 1, 1);
42     }
43 
44     int main()
45     {
46         int T;
47         scanf("%d", &T);
48         int cnt = 0;
49         for(int i=1; i<=MOD; i++)
50             if(MOD%i == 0)
51                 Hash[i] = cnt++;
52         memset(dp, -1, sizeof(dp));
53         while(T--)
54         {
55             long long l, r;
56             scanf("%lld%lld", &l, &r);
57             printf("%lld\n", solve(r)-solve(l-1));
58         }
59         return 0;
60     }