codeforces 691E Xor-sequences(矩阵快速幂)

引自:http://www.cnblogs.com/shuguangzw/p/5674089.html

/* ***********************************************
Author        :devil
************************************************ */
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <cmath>
#include <stdlib.h>
using namespace std;
typedef long long LL;
const int inf=0x3f3f3f3f;
const int mod=1e9+7;
const int N=1e2+10;
LL a[N],k,ans;
int n;
struct Matrix
{
    LL a[N][N];
    Matrix()
    {
        memset(a,0,sizeof(a));
    }
    void init()
    {
        for(int i=1;i<=n;i++)
            a[i][i]=1;
    }
    Matrix operator *(const Matrix &rhs)const
    {
        Matrix ret;
        for(int i=1;i<=n;i++)
            for(int j=1;j<=n;j++)
                for(int k=1;k<=n;k++)
                    ret.a[i][j]=(ret.a[i][j]+a[i][k]*rhs.a[k][j]%mod)%mod;
        return ret;
    }
    Matrix operator ^(LL mi)const
    {
        Matrix tmp=(*this),ret;
        ret.init();
        while(mi)
        {
            if(mi&1)ret=ret*tmp;
            tmp=tmp*tmp;
            mi>>=1;
        }
        return ret;
    }
}cur;
int main()
{
    //freopen("in.txt","r",stdin);
    scanf("%d%I64d",&n,&k);
    for(int i=1; i<=n; i++)
        scanf("%I64d",&a[i]);
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
            if(__builtin_popcountll(a[i]^a[j])%3==0)
                cur.a[i][j]++;
    cur=cur^(k-1);
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
            ans=(ans+cur.a[i][j])%mod;
    printf("%I64d\n",ans);
    return 0;
}

 

posted on 2016-07-22 21:18  恶devil魔  阅读(291)  评论(0编辑  收藏  举报

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