FIBOSUM - Fibonacci Sum
The fibonacci sequence is defined by the following relation:
- F(0) = 0
- F(1) = 1
- F(N) = F(N - 1) + F(N - 2), N >= 2
Your task is very simple. Given two non-negative integers N and M, you have to calculate the sum (F(N) + F(N + 1) + ... + F(M)) mod 1000000007.
The first line contains an integer T (the number of test cases). Then, T lines follow. Each test case consists of a single line with two non-negative integers N and M.
For each test case you have to output a single line containing the answer for the task.
Input: 3 0 3 3 5 10 19 Output: 4 10 10857
- T <= 1000
- 0 <= N <= M <= 109
At last...was fed up with rte.
Negative cases are possible so beware of that.
can be done using partial sum
This is too much cheap!! :/ "N<=M" has been said in constrain. But further they have set input against the constrain in order to make the problem a bit harder. Negative answers never be possible if N<=M. But using this "cout<<(fibonacci(b+2)-fibonacci(a+1)+mod)%mod<<endl; " instead of "cout<<fibonacci(b+2)-fibonacci(a+1)<<endl; " got AC.
I got segmentation fault, please help!
use this to print answers:
negative modulus case was very tricky
Last edit: 2018-05-30 17:14:07
I've learnt matrix exponentiation because of this question