uoj#300.【CTSC2017】吉夫特

题面:http://uoj.ac/problem/300

一道大水题,然而我并不知道$lucas$定理的推论。。

$inom{n}{m}$为奇数的充要条件是$n&m=n$。那么我们对于每个数,直接枚举子集转移就行了,复杂度是$O(3^{18})$,不会$T$。

 1 //It is made by wfj_2048~
 2 #include <algorithm>
 3 #include <iostream>
 4 #include <complex>
 5 #include <cstring>
 6 #include <cstdlib>
 7 #include <cstdio>
 8 #include <vector>
 9 #include <cmath>
10 #include <queue>
11 #include <stack>
12 #include <map>
13 #include <set>
14 #define rhl (1000000007)
15 #define inf (1<<30)
16 #define N (300010)
17 #define il inline
18 #define RG register
19 #define ll long long
20 #define File(s) freopen(s".in","r",stdin),freopen(s".out","w",stdout)
21 
22 using namespace std;
23 
24 int f[N],a[N],b[N],n,ans;
25 
26 il int gi(){
27     RG int x=0,q=1; RG char ch=getchar();
28     while ((ch<'0' || ch>'9') && ch!='-') ch=getchar();
29     if (ch=='-') q=-1,ch=getchar();
30     while (ch>='0' && ch<='9') x=x*10+ch-48,ch=getchar();
31     return q*x;
32 }
33 
34 il void work(){
35     n=gi(); for (RG int i=1;i<=n;++i) a[i]=gi(),b[a[i]]=i;
36     for (RG int i=1;i<=n;++i){
37     ans+=(f[i]++); if (ans>=rhl) ans-=rhl;
38     for (RG int s=a[i];s;s=(s-1)&a[i])
39         if (b[s]>i){ f[b[s]]+=f[i]; if (f[b[s]]>=rhl) f[b[s]]-=rhl; }
40     }
41     printf("%d
",ans); return;
42 }
43 
44 int main(){
45     File("gift");
46     work();
47     return 0;
48 }
原文地址:https://www.cnblogs.com/wfj2048/p/6915527.html