题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=3936
Problem Description We all know the definition of Fibonacci series: fib[i]=fib[i-1]+fib[i-2],fib[1]=1,fib[2]=1.And we define another series P associated with the Fibonacci series: P[i]=fib[4*i-1].Now we will give several queries about P:give two integers L,R, and calculate ∑P[i](L <= i <= R).
Input There is only one test case.
Output For each query output one line.
Sample Input
2 1 300 2 400
Sample Output
838985007 352105429 |
题目大意:斐波那契数列:f[n]=f[n-1]+f[n-2];
令:P[n]=f[4*n-1];
给出q对l,r,求P中[l,r]的对1000000007.取模后的值。
斐波那契数列的性质:https://blog.csdn.net/qq_40482358/article/details/81487345
转换成求斐波那契数列的值
转换过程:
f[1]^2+f[2]^2+f[3]^2+...+f[n]^2=f[n]*f[n+1];
p[i]=f[4*i-1];
p[i]=f[2*i-1]^2+f[2*i]^2;
p[1]=f[1]^2+f[2]^2;
p[2]=f[3]^2+f[4]^2;
sum(p[n])=f[1]^2+f[2]^2+f[3]^2+f[4]^2+...+f[2*n-1]^2+f[2*n]^2;
sum(p[n])=f[2*n]*f[2*n+1];
F(n)=(1/√5)*{[(1+√5)/2]^(n+1) - [(1-√5)/2]^(n+1)}
用矩阵快速幂求值
矩阵快速幂:
ac:
#include<stdio.h>
#include<string.h>
#include<math.h>
#include<map>
//#include<set>
#include<deque>
#include<queue>
#include<stack>
#include<bitset>
#include<string>
#include<iostream>
#include<algorithm>
using namespace std;
#define ll long long
#define INF 0x3f3f3f3f
#define mod 1000000007
//#define max(a,b) (a)>(b)?(a):(b)
//#define min(a,b) (a)<(b)?(a):(b)
#define clean(a,b) memset(a,b,sizeof(a))// 水印
//std::ios::sync_with_stdio(false);
ll temp[3][3],res[3][3],ans[3][3];
void matrix(ll a[][3],ll b[][3])
{
clean(temp,0);
for(int i=1;i<3;++i)
{
for(int j=1;j<3;++j)
{
for(int k=1;k<3;++k)
temp[i][j]=(temp[i][j]+a[i][k] * b[k][j])%mod;
}
}
for(int i=1;i<3;++i)
{
for(int j=1;j<3;++j)
a[i][j]=temp[i][j]%mod;
}
}
void quick(ll n)
{
/*
矩阵快速幂
[a,b,c,d] [a,b,c,d];
[1,1,1,0] [1,1,1,0];
[a*a+b*c , a*b+b*d , a*c+c*d , b*c+d*d]
[1+1,1+0,1+0,1+0]
*/
clean(ans,0);
clean(res,0);
res[1][1]=1;
res[1][2]=1;
res[2][1]=1;
res[2][2]=0;
for(int i=1;i<3;++i)
{
for(int j=1;j<3;++j)
{
if(i==j)
ans[i][j]=1;
else
ans[i][j]=0;
}
}
while(n)
{
if(n&1)
matrix(ans,res);
matrix(res,res);
n=n>>1;
}
}
int main()
{
ll n;
cin>>n;
for(int i=0;i<n;++i)
{
ll l,r;
cin>>l>>r;
ll ans1=0;
if(l==2)
ans1=2;
if(l>2)
{
quick(2*l-2-2);
ans1=(ans[1][1]+ans[2][1])%mod;
quick(2*l-2-2+1);
ans1=(ans1*((ans[1][1]+ans[2][1])%mod))%mod;
}
ll ans2=0;
quick(2*r-2);
ans2=(ans[1][1]+ans[2][1])%mod;
quick(2*r-2+1);
ans2=(ans2*((ans[1][1]+ans[2][1])%mod))%mod;
cout<<(ans2-ans1+mod)%mod<<endl;
}
}