codeforces#P1635D. Infinite Set
Infinite Set
Description
You are given an array $a$ consisting of $n$ distinct positive integers.
Let's consider an infinite integer set $S$ which contains all integers $x$ that satisfy at least one of the following conditions:
- $x = a_i$ for some $1 \leq i \leq n$.
- $x = 2y + 1$ and $y$ is in $S$.
- $x = 4y$ and $y$ is in $S$.
For example, if $a = [1,2]$ then the $10$ smallest elements in $S$ will be $\{1,2,3,4,5,7,8,9,11,12\}$.
Find the number of elements in $S$ that are strictly smaller than $2^p$. Since this number may be too large, print it modulo $10^9 + 7$.
The first line contains two integers $n$ and $p$ $(1 \leq n, p \leq 2 \cdot 10^5)$.
The second line contains $n$ integers $a_1,a_2,\ldots,a_n$ $(1 \leq a_i \leq 10^9)$.
It is guaranteed that all the numbers in $a$ are distinct.
Print a single integer, the number of elements in $S$ that are strictly smaller than $2^p$. Remember to print it modulo $10^9 + 7$.
Input
The first line contains two integers $n$ and $p$ $(1 \leq n, p \leq 2 \cdot 10^5)$.
The second line contains $n$ integers $a_1,a_2,\ldots,a_n$ $(1 \leq a_i \leq 10^9)$.
It is guaranteed that all the numbers in $a$ are distinct.
Output
Print a single integer, the number of elements in $S$ that are strictly smaller than $2^p$. Remember to print it modulo $10^9 + 7$.
Samples
2 4
6 1
9
4 7
20 39 5 200
14
2 200000
48763 1000000000
448201910
Note
In the first example, the elements smaller than $2^4$ are $\{1, 3, 4, 6, 7, 9, 12, 13, 15\}$.
In the second example, the elements smaller than $2^7$ are $\{5,11,20,23,39,41,44,47,79,80,83,89,92,95\}$.