Python calculation prime learning record

Calculate prime numbers in a certain range , And recorded in json In file . The next calculation can be based on the last iteration

In from 3 In the case of starting to calculate prime numbers , Calculation 100 Prime numbers within ten thousand can be 1 seconds

import
json


import
time


start
=
time.
time()


limit
=
1e6


try:


with
open (
'prime.json',
'r')
as
file:


list
=
json.
load(
file)


num
=
list[
-
1]


except
FileNotFoundError:


list
= [
3]


num
=
3




def
check(
num):


for
i
in
list:


if
num
%
i
==
0:


break


elif
i
*
i
>
num:
# Don't write here i**2, The calculation speed will be slow 2 More than double 


list.
append(
num)


#print(num)


break




while
num
<
limit:


num
=
num
+
2


check(
num)




# with open ('prime.json', 'w') as file:


# json.dump(list,file,indent=4)




print(
list[
-
1])


end
=
time.
time()


print(
f' Time for this calculation ：{
end
-
start}
')


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i5-6200U Calculation time ：