bzoj1853 [Scoi2010]幸运数字

Posted 2020-06-14

题目链接

容斥原理

虽然只含6、8的数有很多

但是题解告诉我真正互质的只有10+个woc

然后容斥原理，注意爆long long ，用double 近似比较

 1 #include<algorithm>
 2 #include<iostream>
 3 #include<cstdlib>
 4 #include<cstring>
 5 #include<cstdio>
 6 #include<string>
 7 #include<cmath>
 8 #include<ctime>
 9 #include<queue>
10 #include<stack>
11 #include<map>
12 #include<set>
13 #define rre(i,r,l) for(int i=(r);i>=(l);i--)
14 #define re(i,l,r) for(int i=(l);i<=(r);i++)
15 #define Clear(a,b) memset(a,b,sizeof(a))
16 #define inout(x) printf("%d",(x))
17 #define douin(x) scanf("%lf",&x)
18 #define strin(x) scanf("%s",(x))
19 #define LLin(x) scanf("%lld",&x)
20 #define op operator
21 #define CSC main
22 typedef unsigned long long ULL;
23 typedef const int cint;
24 typedef long long LL;
25 using namespace std;
26 void inin(int &ret)
27 {
28     ret=0;int f=0;char ch=getchar();
29     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=1;ch=getchar();}
30     while(ch>=‘0‘&&ch<=‘9‘)ret*=10,ret+=ch-‘0‘,ch=getchar();
31     ret=f?-ret:ret;
32 }
33 LL l,r,a[10010],b[10010],top,n,ans;
34 bool bo[10010];
35 LL gcd(LL a,LL b)
36 {
37     LL c;
38     while(a%b)c=a%b,a=b,b=c;
39     return b;
40 }
41 void hh(int aa,LL bb)
42 {
43     if(bb>r)return ;
44     if(aa>0)a[++top]=bb;
45     hh(aa+1,bb*10+6);
46     hh(aa+1,bb*10+8);
47 }
48 void dfs(int aa,int bb,LL cc)
49 {
50     if(aa>n)
51     {
52         if(bb&1)ans+=r/cc-l/cc;
53         else if(bb)ans-=r/cc-l/cc;
54         return;
55     }
56     dfs(aa+1,bb,cc);
57     LL temp=cc/gcd(a[aa],cc);
58     if(((long double)a[aa]*temp)<=r)
59        dfs(aa+1,bb+1,a[aa]*temp);
60 }
61 int CSC()
62 {
63     LLin(l),LLin(r);
64     hh(0,0);
65     sort(a+1,a+top+1);
66     re(i,1,top)if(!bo[i])
67     {
68         b[++n]=a[i];
69         re(j,i+1,top)if(!a[j]%a[i])bo[j]=1;
70     }
71     re(i,1,n)a[n-i+1]=b[i];l--;
72     dfs(1,0,1);
73     printf("%lld",ans);
74     return 0;
75 }