Q:
By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.
What is the 10001st prime number?
My code is:
def is_prime(num):
if all(num % i != 0 for i in range(2, num)):
return True
else:
return False
def find_nth_prime(nth):
lst_prime = []
num = 2
while len(lst_prime) < nth:
if is_prime(num):
lst_prime.append(num)
print(len(lst_prime), ":", lst_prime[-1])
num += 1
When I try to run find_nth_prime(6) it get stuck after finding "3" as prime. What am I missing here?
>Solution :
In your if statement inside while loop it keeps repeating at n=4 since n +=1 never happens as 4 is not a prime. Therefore take it out of the if statement.
Try using https://pythontutor.com/. It helps you visualize your code
def find_nth_prime(nth):
lst_prime = []
num = 2
while len(lst_prime) < nth:
if is_prime(num):
lst_prime.append(num)
print(len(lst_prime), ":", lst_prime[-1])
num += 1
Also you can do some improvments to your is_prime function. In that you don’t have to take the whole range (2, num). It is enough to take the range 2 to square root of num. (2,int(num**0.5)+1) or use sqrt from python’s math library