LightOJ 1140 How Many Zeroes

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cstdlib>
 5 #include<cmath>
 6 #include<algorithm>
 7 #define inf 0x7fffffff
 8 #define exp 1e-10
 9 #define PI 3.141592654
10 using namespace std;
11 typedef long long LL;
12 LL digit[21];
13 LL dp[21][2][21];
14 LL dfs(LL len,bool flag,LL p,LL p2,bool fp)
15 {
16     if (!len)
17     {
18         if (!flag)
19         return p2-p;
20         else return 0;
21     }
22     if (!fp && dp[len][flag][p2-p]!=-1) return dp[len][flag][p2-p];
23     LL ret=0;
24     LL fpmax= fp ? digit[len] : 9 ;
25     for (LL i=0 ;i<=fpmax ;i++)
26     {
27         bool ok= i==0 ? true : false;
28         LL temp;
29         if (i==0) temp=1 ; else temp=0 ;
30         ret += dfs(len-1,flag&&ok,flag?p+temp:p ,p2+temp,fp&&i==fpmax);
31     }
32     if (!fp) return dp[len][flag][p2-p]=ret;
33     return ret;
34 }
35 LL f(LL n)
36 {
37     if (n==-1) return -1;
38     if (n==0) return 0;
39     LL len=0;
40     while (n)
41     {
42         digit[++len]=n%10;
43         n /= 10;
44     }
45     return dfs(len,true,0,0,true);
46 }
47 int main()
48 {
49     int t;
50     int ncase=1;
51     cin>>t;
52     while (t--)
53     {
54         LL a,b;
55         scanf("%lld%lld",&a,&b);
56         memset(dp,-1,sizeof(dp));
57         printf("Case %d: %lld\n",ncase++,f(b)-f(a-1));
58     }
59     return 0;
60 }