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
Surya Sekhar Mondal:
use long long , cost me 3 WAs
use modulus while matrix multiplication and at final answer and take care of neg modulus too :)
AC in one go..
NEGATIVE MODULUS COST ME 2WA
nice problem ^_^
When i was using modulo only at answer(final ans) time got TLE.
Try taking out a recurrence for S(n) rather than expressing the sum in fibbonaci term.... Will make you feel better surely :)
My 60th :) Use long datatype...int cost me WAs
log(n) + be careful of the negative mod.. :)