70 lines
1.4 KiB
C++
70 lines
1.4 KiB
C++
#include <bits/stdc++.h>
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using namespace std;
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const long long MOD = 1000000007LL;
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struct Mat {
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long long a[105][105];
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int n, m;
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Mat(int _n = 0, int _m = 0) : n(_n), m(_m) {
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memset(a, 0, sizeof(a));
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}
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void operator*=(const Mat &b) {
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if (m != b.n) {
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cerr << "矩阵维度不匹配" << endl;
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exit(-1);
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}
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long long res[105][105] = {};
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for (int i = 1; i <= n; ++i) {
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for (int j = 1; j <= b.m; ++j) {
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for (int k = 1; k <= m; ++k) {
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res[i][j] = (res[i][j] + a[i][k] * b.a[k][j]) % MOD;
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}
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}
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}
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for (int i = 1; i <= n; ++i) {
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for (int j = 1; j <= b.m; ++j) {
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a[i][j] = res[i][j];
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}
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}
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m = b.m;
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}
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};
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Mat qpow(Mat a, long long k) {
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Mat res(a.n, a.n);
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for (int i = 1; i <= a.n; ++i) {
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res.a[i][i] = 1;
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}
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while (k) {
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if (k & 1) res *= a;
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a *= a;
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k >>= 1;
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}
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return res;
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}
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int main() {
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long long n;
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scanf("%lld", &n);
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if (n <= 2) {
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printf("1\n");
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return 0;
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}
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Mat base1(1, 2), base2(2, 2);
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base1.a[1][1] = 1;
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base1.a[1][2] = 1;
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base2.a[1][1] = 1;
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base2.a[1][2] = 1;
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base2.a[2][1] = 1;
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base2.a[2][2] = 0;
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base2 = qpow(base2, n - 2);
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base1 *= base2;
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printf("%lld\n", base1.a[1][1]);
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return 0;
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} |