Another kind of Fibonacci(hdu3306)
阅读原文时间:2023年07月12日阅读:1

Another kind of Fibonacci

**Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 2353    Accepted Submission(s): 936
**

Problem Description

As
we all known , the Fibonacci series : F(0) = 1, F(1) = 1, F(N) = F(N -
1) + F(N - 2) (N >= 2).Now we define another kind of Fibonacci : A(0)
= 1 , A(1) = 1 , A(N) = X * A(N - 1) + Y * A(N - 2) (N >= 2).And we
want to Calculate S(N) , S(N) = A(0)2 +A(1)2+……+A(n)2.

Input

There are several test cases.
Each test case will contain three integers , N, X , Y .
N : 2<= N <= 231 – 1
X : 2<= X <= 231– 1
Y : 2<= Y <= 231 – 1

Output

For each test case , output the answer of S(n).If the answer is too big , divide it by 10007 and give me the reminder.

Sample Input

2 1 1

3 2 3

Sample Output

6

196

 思路:矩阵快速幂;

S(n) = ∑f(n)2 = S(n-1)+f(n)2 = S(n-1)+x2f(n-1)2+y2f(n-2)2+2xyf(n-1)f(n-2);

然后f(n)*f(n-1) = (x*f(n-1)+y*f(n-2))*f(n-1) = x*f(n-1)2+y*f(n-1)*f(n-2);

然后构造矩阵;

其中的第三个矩阵写错了,应该是s[n-1];     f[n-1]^2;     f[n-2]^2;  f[n-1]*f[n-2];

1 #include
2 #include
3 #include
4 #include
5 #include
6 #include
7 #include
8 #include
9 using namespace std;
10 typedef struct node
11 {
12 int m[4][4];
13 node()
14 {
15 memset(m,0,sizeof(m));
16 }
17 } maxtr;
18 void Init(maxtr *ans,int x,int y);
19 maxtr E();
20 maxtr quick_m(maxtr ak,int m);
21 const int mod = 10007;
22 int main(void)
23 {
24 int n,x,y;
25 while(scanf("%d %d %d",&n,&x,&y)!=EOF)
26 {
27 int f1 = 2;
28 int a1 = 1;
29 int a0 = 1;
30 int xx = 1;
31 maxtr ask ;
32 Init(&ask,x,y);
33 maxtr tp = quick_m(ask,n-1);
34 printf("%d\n",(tp.m[0][0]*2+tp.m[0][1]*a1+tp.m[0][2]*a0+tp.m[0][3]*xx)%mod);
35 }
36 return 0;
37 }
38 void Init(maxtr *ans,int x,int y)
39 { memset(ans->m,0,sizeof(ans->m));
40 x%=mod;y%=mod;
41 ans->m[0][0] = 1;
42 ans->m[0][1] = x*x%mod;
43 ans->m[0][2] = y*y%mod;
44 ans->m[0][3] =2*x*y%mod;
45 ans->m[1][1] = x*x%mod;
46 ans->m[1][2] = y*y%mod;
47 ans->m[1][3] = 2*x*y%mod;
48 ans->m[2][1] = 1;
49 ans->m[3][1] = x%mod;
50 ans->m[3][3] = y%mod;
51 }
52 maxtr E()
53 {
54 maxtr ak;
55 int i,j;
56 for(i = 0; i < 4; i++) 57 { 58 for(j = 0; j < 4; j++) 59 { 60 if(i == j) 61 ak.m[i][j] = 1; 62 } 63 } 64 return ak; 65 } 66 maxtr quick_m(maxtr ak,int m) 67 { 68 int i,j; 69 maxtr ac = E(); 70 while(m) 71 { 72 if(m&1) 73 { 74 maxtr a; 75 for(i = 0; i < 4; i++) 76 for(j = 0; j < 4; j++) 77 for(int s= 0; s < 4; s++) 78 a.m[i][j] = (a.m[i][j] + ak.m[i][s]*ac.m[s][j]%mod)%mod; 79 ac = a; 80 } 81 maxtr b; 82 for(i = 0; i < 4; i++) 83 for(j = 0; j < 4; j++) 84 for(int s = 0; s < 4; s++) 85 b.m[i][j] = (b.m[i][j] + ak.m[i][s]*ak.m[s][j]%mod)%mod; 86 ak = b; 87 m>>=1;
88 }
89 return ac;
90 }

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