Preparing NOJ

Ayoub had an array $$$a$$$ of integers of size $$$n$$$ and this array had two interesting properties:

- All the integers in the array were between $$$l$$$ and $$$r$$$ (inclusive).
- The sum of all the elements was divisible by $$$3$$$.

Unfortunately, Ayoub has lost his array, but he remembers the size of the array $$$n$$$ and the numbers $$$l$$$ and $$$r$$$, so he asked you to find the number of ways to restore the array.

Since the answer could be very large, print it modulo $$$10^9 + 7$$$ (i.e. the remainder when dividing by $$$10^9 + 7$$$). In case there are no satisfying arrays (Ayoub has a wrong memory), print $$$0$$$.

The first and only line contains three integers $$$n$$$, $$$l$$$ and $$$r$$$ ($$$1 \le n \le 2 \cdot 10^5 , 1 \le l \le r \le 10^9$$$) — the size of the lost array and the range of numbers in the array.

Print the remainder when dividing by $$$10^9 + 7$$$ the number of ways to restore the array.

2 1 3

3

3 2 2

1

9 9 99

711426616

In the first example, the possible arrays are : $$$[1,2], [2,1], [3, 3]$$$.

In the second example, the only possible array is $$$[2, 2, 2]$$$.

Info

Provider CodeForces

Origin Codeforces Round #533 (Div. 2)

Code CF1105C

Tags

combinatoricsdpmath

Submitted 92

Passed 33

AC Rate 35.87%

Date 03/04/2019 16:49:38

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