Problem 981. Find nearest prime number less than input number

Created by Reza Ahmadzadeh

Solve Later

Find nearest prime number less than input number.

For example: if the input number is 125, then the nearest prime number which is less than this number is 113.

Be careful, in that 1 is not a prime number. So there is NO prime less than 2.

Solve

Solution Stats

631 Solutions
175 Solvers

Last Solution submitted on Nov 18, 2019

Last 200 Solutions

Problem Comments

6 Comments

6 Comments

Show 3 older comments

@bmtran (Bryant Tran) on 10 Oct 2012

1 isn't a prime number

Disha on 31 Jul 2013

agree @bmtran...

Grzegorz Knor on 20 Sep 2013

You should correct the test suite. 1 isn't a prime number.

Vishal on 6 Oct 2014

Correct the test suite 1 is not prime number.

Daniel Pereira on 6 May 2016

1 is not a prime number, in order to fulfill with the fundamental theorem of arithmetic:

https://en.wikipedia.org/wiki/Fundamental_theorem_of_arithmetic

https://en.wikipedia.org/wiki/Prime_number#Primality_of_one

John D'Errico on 22 Feb 2018

I removed the test case where n==2, since 1 is indeed not a prime number. I also added a random test case, so the problem is not so easily cooked by knowing all the test cases.

Solution Comments

Solution 1243365

1 Comment

1 Comment

Yinghui Li on 1 Aug 2017

Well I think number 1 is not a prime number, but I need to pass the test. So I wander all the right answer may be possibly wrong since you have 1.

Solution 840982

1 Comment

1 Comment

eggart on 2 Mar 2016

IMHO 1 is not a prime, so that on input n=2 the correct answer should be [] and not 1.

Solution 752761

1 Comment

1 Comment

Takehiko KOBORI on 4 Oct 2015

これで正しいだろ。

Solution 489950

2 Comments

2 Comments

bainhome on 24 Aug 2014

you still not change the wrong test suite:4.1 is not a prime.

Gareth Lee on 30 Apr 2015

agree with bainhome

Problem Recent Solvers175

Problem Tags

math prime numbers

Problem 981. Find nearest prime number less than input number

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers175

Suggested Problems

More from this Author11

Problem Tags

Problem 981. Find nearest prime number less than input number

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers175

Suggested Problems

More from this Author11

Problem Tags

Players