-
Notifications
You must be signed in to change notification settings - Fork 1
/
13976.cpp
37 lines (31 loc) · 801 Bytes
/
13976.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
#include <iostream>
#include <vector>
#define MOD 1000000007
using namespace std;
using Matrix = vector<vector<long long>>;
Matrix matmul(const Matrix &a, const Matrix &b) {
Matrix c(2, vector<long long>(2, 0));
for (int i=0; i<2; i++) for (int j=0; j<2; j++) for (int k=0; k<2; k++) {
c[i][j] = (c[i][j] + a[i][k] * b[k][j] + MOD) % MOD;
}
return c;
}
Matrix matpow(Matrix base, long long exp) {
Matrix ret = {{1, 0}, {0, 1}};
while (exp) {
if (exp & 1) ret = matmul(ret, base);
base = matmul(base, base);
exp >>= 1;
}
return ret;
}
void solve(void) {
long long n; cin >> n;
cout << (n & 1 ? 0 : matmul(matpow({{0, 1}, {-1, 4}}, n >> 1), {{1, 0}, {3, 0}})[0][0]);
}
int main(void) {
ios::sync_with_stdio(false);
cin.tie(nullptr);
solve();
return 0;
}