---
# System prepended metadata

title: 'level 5:Gap in Primes(2019-11-29)'
tags: [python, Codewars]

---

# level 5:Gap in Primes(2019-11-29)
###### tags: `Codewars` `python`

The prime numbers are not regularly spaced. For example from 2 to 3 the gap is 1. From 3 to 5 the gap is 2. From 7 to 11 it is 4. Between 2 and 50 we have the following pairs of 2-gaps primes: 3-5, 5-7, 11-13, 17-19, 29-31, 41-43

A prime gap of length n is a run of n-1 consecutive composite numbers between two successive primes (see: http://mathworld.wolfram.com/PrimeGaps.html).

We will write a function gap with parameters:

g (integer >= 2) which indicates the gap we are looking for

m (integer > 2) which gives the start of the search (m inclusive)

n (integer >= m) which gives the end of the search (n inclusive)

In the example above gap(2, 3, 50) will return [3, 5] or (3, 5) or {3, 5} which is the first pair between 3 and 50 with a 2-gap.

So this function should return the first pair of two prime numbers spaced with a gap of g between the limits m, n if these numbers exist otherwise nil or null or None or Nothing (depending on the language).

In C++ return in such a case {0, 0}. In F# return [||]. In Kotlin return []

#Examples: gap(2, 5, 7) --> [5, 7] or (5, 7) or {5, 7}

gap(2, 5, 5) --> nil. In C++ {0, 0}. In F# [||]. In Kotlin return[]`

gap(4, 130, 200) --> [163, 167] or (163, 167) or {163, 167}

([193, 197] is also such a 4-gap primes between 130 and 200 but it's not the first pair)

gap(6,100,110) --> nil or {0, 0} : between 100 and 110 we have 101, 103, 107, 109 but 101-107is not a 6-gap because there is 103in between and 103-109is not a 6-gap because there is 107in between.

#### my code:
<pre>
def primeornot(number):
    tof = True
    for i in range(2,number):
        if number%i == 0:
            tof = False
    return tof

def gap(g, m, n):
    beginnumber = 0
    endnumber = 0
    for i in range(m,n):
        if primeornot(i) == True:
            if beginnumber == 0:
                beginnumber = i
            elif endnumber == 0:
                endnumber = i
            else:
                beginnumber = endnumber
                endnumber = i
            if (endnumber-beginnumber == g):
                return[beginnumber, endnumber]
    return None
</pre>