NINJA5 - K NUMBERS

You are given N numbers from 1 to N. Now, your task is to choose some numbers from the N numbers (including 1 and N) such that no two numbers are consecutive. As this is easy, you are given an extra task. You have to definitely choose K numbers which are given. Find the maximum number of numbers that you can choose in such a way.

Input:

The first line has an integer T, the number of test cases.

Then for each test case, the first line has two integers N and K.

Then the next line has K numbers which you should definitely choose.

Output:

For each test case, print the maximum number of numbers that you can choose.

Constraints:

1 <= T <= 100

2 <= N <= 2 x 10^6

1 <= K <= N / 2

1 <= X[1...K] <= N

Sample

Input:
1
8 2
6 2

Output:
4


Added by:mombassa
Date:2016-02-17
Time limit:0.200s-1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ASM64 GOSU JS-MONKEY

hide comments
2024-02-19 04:38:03
@smso is right as of now. Those K numbers will always be included even if any pair of K numbers are consecutive.
2019-04-15 11:28:34
my accepted codes give:
1
5 5
1 2 3 4 5
output:
5
2018-11-17 09:11:59
if any of the two given K numbers are already consecutive, then just print 0. Worked for me!
2018-04-24 19:47:04
Can't pass in raw Python and O(klogk) slower than O(n) in PyPy. Poorly set problem.
2017-07-23 07:15:50
Very easy.AC in one go.O(n) solution exists.
2017-06-20 07:06:23
no sorting :) just take char array of size max n.and O(n+t)solution
2017-06-18 12:28:34
qsort giving TLE why? @himanshuz1

Last edit: 2017-06-18 12:33:46
2016-10-28 13:28:50
need to tighten the time.... O(n) easily excepted
2016-07-21 13:39:17 himanshu kumar
O(n+k) solution passes it easily... while sorting gives tle
2016-07-04 07:51:27
My code does not account for the already selected numbers being consecutive
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