'commit'

TangDou/AcWingSuanFaJinJieZhiNan/P1962.cpp

@@ -0,0 +1,46 @@
+#include <bits/stdc++.h>
+using namespace std;
+typedef long long LL;
+const int N = 10;
+const int MOD = 1e9 + 7;
+
+LL base[N][N], res[N][N];
+
+inline void mul(LL C[][N], LL A[][N], LL B[][N]) {
+    static LL tmp[N][N];
+    memset(tmp, 0, sizeof(tmp));
+    for (int i = 1; i <= 2; i++)
+        for (int j = 1; j <= 2; j++)
+            for (int k = 1; k <= 2; k++)
+                tmp[i][j] = (tmp[i][j] + (A[i][k] * B[k][j]) % MOD) % MOD;
+    memcpy(C, tmp, sizeof tmp);
+}
+
+//快速幂
+inline void qmi(LL k) {
+    //初始化结果数组的(i,i)=1
+    memset(res, 0, sizeof res);
+    res[1][1] = res[1][2] = 1;
+    while (k) {
+        if (k & 1) mul(res, res, base);
+        mul(base, base, base);
+        k >>= 1;
+    }
+}
+
+int main() {
+    LL n;
+    cin >> n;
+    if (n <= 2) {
+        puts("1");
+        return 0;
+    }
+    //结果矩阵初始化
+    memset(base, 0, sizeof base);
+    base[1][1] = base[1][2] = base[2][1] = 1;
+    //快速幂
+    qmi(n - 2);
+    //结果
+    cout << (res[1][1]) % MOD << endl;
+    return 0;
+}