'commit'

TangDou/AcWingSuanFaJinJieZhiNan/P1962_JZ.cpp

@@ -0,0 +1,53 @@
+#include <bits/stdc++.h>
+using namespace std;
+typedef long long LL;
+const int N = 10;
+const int MOD = 1e9 + 7;
+
+//矩阵声明
+struct JZ {
+    LL m[N][N];
+} res, base;
+
+inline JZ mul(JZ A, JZ B) {
+    JZ C;
+    memset(C.m, 0, sizeof(C.m));
+    for (int i = 1; i <= 2; i++)
+        for (int j = 1; j <= 2; j++)
+            for (int k = 1; k <= 2; k++) {
+                C.m[i][j] = (C.m[i][j] + (A.m[i][k] * B.m[k][j]) % MOD) % MOD;
+            }
+    return C;
+}
+
+//快速幂
+inline void qmi(LL k) {
+    memset(res.m, 0, sizeof res.m);
+    res.m[1][1] = res.m[1][2] = 1; // f(1)=1,f(2)=1 乘一次矩阵就是f(3),所以f(n)就是n-2次方
+    while (k) {
+        if (k & 1) res = mul(res, base);
+        base = mul(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.m, 0, sizeof base.m);
+    base.m[1][1] = base.m[1][2] = base.m[2][1] = 1;
+    /*
+    1 1
+    1 0
+    base 矩阵
+    */
+    //快速幂
+    qmi(n - 2);
+    //结果
+    cout << (res.m[1][1]) % MOD << endl;
+    return 0;
+}