I have created the below script to find out the prime factors of a number :
def check_if_no_is_prime(n):
if n <= 3:
return True
else:
limit = int(math.sqrt(n))
for i in range(2,limit + 1):
if n % i == 0:
return False
return True
def find_prime_factors(x):
prime_factors = []
if check_if_no_is_prime(x):
prime_factors.append(1)
prime_factors.append(x)
else:
while x % 2 == 0 and x > 1:
prime_factors.append(2)
x = x // 2
for i in range(3,x+1,2):
while x % i == 0 and x > 1:
if check_if_no_is_prime(i):
prime_factors.append(i)
x = x // i
if x <= 1:
return prime_factors
return prime_factors
no = int(input())
check = find_prime_factors(no)
print (check)
I am not sure whether this is the best and efficient way to do this ?
Can someone please point out any better way to do this ?
using sieve of erathnostanes to get all prime numbers from 2 to whatever limit inputted
def sieve(N):
from math import floor,sqrt
A=[1 for x in range(N+1)]
for count in range(2):
A[count]=0
for i in range(floor(sqrt(N))+1):
if A[i]==1:
for k in range(i*i,N+1,i):
A[k]=0
ans=list(enumerate(A))
res=[]
for (i,j) in ans:
if j==1:
res+=[i]
return res
print(sieve(100))
#my code
Related
This code works but it is not very efficient is there any help on a faster code in python to find n knowing that n is an integer above 0 and that n has no upper bound, how(x) will return you 1 if x>n, 0 if x = n, and -1 if x
def how(x):
if x > n:
return 1
elif x < n:
return -1
else:
return 0
def find(how):
if how(1) == 1:
return 1
x = 2
while how(x) != 1:
x = x**x
v = x
while how(x) != 0:
if how(x) == 1:
v = x
x = (x+1)//2
else:
x += (v-x+1)//2
return x
Rebecca, I've added some print statements so you can see where goes what wrong. As Patrick Artner said... its a bit confusing which way to go so I've tried to clean-up some things that enable you to continue exploring comparison of two variables against each other (and fake error catching (0).
Lets start and remove the confusing lingo and produce something workable code. With current below script it runs and with value = 1, reference = 1 you get the below print result in a continues loop until YOU stop the script manually:
v1 = n: error
loop1 1
def selector(v1, n):
if v1 > n:
print 'v1 > n', v1, n
return 1
elif v1 < n:
print 'v1 < n', v1, n
return -1
else:
print 'v1 == n: error'
return 0
def find(value, reference):
if selector(value, reference) == 1:
return 1
while selector(value, reference) != 1:
x = value**value
print 'loop1', x
v = x
while selector(value, reference) != 0:
print 'loop2'
if selector(value, reference) == 1:
v = value
x = (value+1)/2
print 'loop2-if', v, x
else:
x += (v-(value+1))/2
print 'loop2-else', x
print ' Almost done...'
return x
if __name__ == '__main__':
n = 1
print find(1, 1)
Happy exploring,....
This code is to convert decimals to binary.
What I'm trying to do is to chop off the decimal part after diving by 2.
binary = []
n = 25
while n != 0:
binary.append(n % 2)
n = n / 2
int(n) #this part
print(binary)
print(n)
choose = input("continue?[Y/N]")
if choose == 'y':
continue
else:
break
print(list(reversed(binary)))
Is this what you want?
binary = []
n = 25
while n != 0:
binary.append(n % 2)
n = n / 2
n = int(n) #assign result to n
print(binary)
print(n)
choose = input("continue?[Y/N]")
if choose == 'y':
continue
else:
break
print(list(reversed(binary)))
I've tested to see if the list is empty and I'm sure it's not empty. So why this error continues?
The code is to find the smallest amount of factorial to a sum is equal to N.
def fat(n):
if n == 0 or n == 1:
return 1
else:
return n * fat(n - 1)
n = int(input())
ns = [x+1 for x in range(n)]
listaFat = []
l = []
for x in ns:
if fat(x) < n:
listaFat.append(x)
maior = max(listaFat)
listaFat.remove(maior)
print(listaFat)
print(len(listaFat))
while (fat(listaFat[-1]) + fat(maior)) < n:
l.append(listaFat[-1])
if len(listaFat) > 0:
listaFat.remove(listaFat[-1])
continue
else: break
print(l)
print(listaFat)
I am doing an assignment and the answers are coming back correctly but I would need them to say 5! = 120 instead of just = 120. How would I go about that?
def getInt():
getInt = int
done = False
while not done:
print("This program calcultes N!")
# get input for "N
N = int(input("Please enter a non-negative value for N: "))
if N < 0:
print("Non-Negative integers, please!")
else:
done = True
return N
def main():
n = getInt()
for i in range(n-1):
n = n * (i+1)
print("=" ,n)
main()
I hope this code will help.
print('Enter a positive integer')
a = int(input())
def factorial(n):
if n == 0:
return(1)
if n == 1:
return(1)
if n > 1:
return(n * factorial(n-1))
if a < 0:
print('Non-Negative integers, please!')
if a >= 0:
print(str(a) + '! = ' + str(factorial(a)))
In the for i in range(n-1)you could use another integer instead of n just to be sure things don't mess up and you can print like joel said print(i,"!=", n) but instead of n the integer you will use.
can you show me your homework instructions?
i'm not sure what the first value is in your example.. the current iteration or the original number entered?
# declare getInt()
def getInt():
getInt = int
done = False
while not done:
# write "this program calculates N!"
print("This program calcultes N!")
# get input for "N
N = int(input("Please enter a non-negative value for N: "))
# if N < 0 then
if N < 0:
print("Non-Negative integers, please!")
# else
else:
# done = true
done = True
# return N
return N
# main
def main():
n = entry = getInt()
for i in range(n-1):
n = n * (i+1)
print("{0}! = {1}".format(entry, n))
main()
results:
/*
This program calcultes N!
Please enter a non-negative value for N: 5
5! = 120
*/
def primetest(x):
if x < 2:
return False
if x == 2:
return True
if x % 2 == 0:
return False
for i in range(3,(x**0.5)+1):
if x % i == 0:
return False
return True
def nthprime(n):
primes = []
x = 2
while len(primes) < n:
if primetest(x) == True:
primes.append(x)
x = x + 1
return list(-1)
print nthprime(10001)
Whenever I try to run this it says that "print nthprime(10001)" is invalid syntax.
-prime test is to test wether a number is prime and nthprime creates a list of prime numbers a certain lengths and then return the last element of the list.
print is a function in Python 3, not a statement. You should change your last line of code to:
print(nthprime(10001))
In your code:
def nthprime(n):
primes = []
x = 2
while len(primes) < n:
if primetest(x) == True:
primes.append(x)
x = x + 1
return list(-1) // this is the error
I think you meant primes[-1], like this:
def nthprime(n):
primes = []
x = 2
while len(primes) < n:
if primetest(x) == True:
primes.append(x)
x = x + 1
return primes[-1] // this is now correct
You're also going to need to specify a range in integers, not float. So this:
for i in range(3,(x**0.5)+1):
Becomes this:
for i in range(3,int((x**0.5)+1)): // note the "int"