Bzoj 2393 Cirno's Perfect arithmetic classroom (principle of repulsion + search)

Test instructions

Defines the number of C numbers that contain only numbers 2 and 9, and the number of [l,r] that are divisible by C numbers.

Ideas

DFS preprocessed a number of C and removed multiple cases.

DFS search occurrences, odd plus, even minus, when the value is greater than R pruning.

Code

1#include <cstdio>2#include <cstring>3#include <algorithm>4 using namespacestd;5 6typedefLong Longll;7 Const intN = 2e3+Ten;8 9 ll A[n],b[n],vis[n],ans,tot,n,l,r;Ten  One voidGet_pre (intnum) A { -     if(Num>r)return ; -     if(num) a[++tot]=num; theGet_pre (num*Ten+2); -Get_pre (num*Ten+9); - } - ll gcd (ll A,ll b) + { -     returnb==0? A:GCD (b,a%b); + } A voidDfsintCurintcnt,ll LCM) at { -     if(cur==n+1) { -         if(cnt&1) ans+=r/lcm-(l1)/LCM; -         Else if(CNT) ans-=r/lcm-(L-1)/LCM; -         return ; -     } inDFS (cur+1, CNT,LCM); -ll val=lcm*a[cur]/(GCD (Lcm,a[cur])); to     if(val<=r) DFS (cur+1, cnt+1, Val); + } -  the intMain () * { $scanf"%lld%lld",&l,&R);Panax NotoginsengGet_pre (0); -Sort (A +1, a+tot+1); the      for(intI=1; i<=tot;i++) +     if(!Vis[i]) { Ab[++n]=A[i]; the          for(intj=i+1; j<=tot;j++) +             if(a[j]%a[i]==0) vis[j]=1;  -     } $      for(intI=1; i<=n;i++) $a[i]=b[n-i+1]; -Dfs1,0,1); -printf"%lld\n", ans); the     return 0; -}

Bzoj 2393 Cirno's Perfect arithmetic classroom (principle of repulsion + search)