Codeforces 691E Xor-sequences(思维)

#include <bits/stdc++.h>

using namespace std;

#define rep(i, a, b)              for(int i(a); i <= (b); ++i)

struct Matrix{ long long  arr[105][105];}  init, unit;
long long k, ret, mod = 1e9 + 7;
long long a[105];
int n;

Matrix Mul(Matrix a, Matrix b){
    Matrix c;
    rep(i, 1, n) rep(j, 1, n){
        c.arr[i][j] = 0;
        rep(k, 1, n) (c.arr[i][j] += (a.arr[i][k] * b.arr[k][j] % mod)) %= mod;
    }
    return c;
}

Matrix Pow(Matrix a, long long  k){
    Matrix ret(unit); for (; k; k >>= 1, a = Mul(a, a)) if (k & 1) ret = Mul(ret, a); return ret;
}    

inline long long check(long long x){
    int ret = 0;
    for (; x; x >>= 1) ret += (x & 1);
    return ret % 3 == 0;
}

int main(){

    scanf("%d%lld", &n, &k);
    rep(i, 1, n) unit.arr[i][i] = 1;
    rep(i, 1, n) scanf("%lld", a + i);
    rep(i, 1, n) rep(j, 1, n) init.arr[i][j] = check(a[i] ^ a[j]);
    Matrix Ans = Pow(init, k - 1); ret = 0;
    rep(i, 1, n) rep(j, 1, n) (ret += Ans.arr[i][j]) %= mod;
    printf("%lld\n", ret);

    return 0;

}