I have been working on Project Euler #23.
This is the task:
Problem 23
A perfect number is a number for which the sum of its proper divisors is exactly equal to the number. For example, the sum of the proper divisors of 28 would be 1 + 2 + 4 + 7 + 14 = 28, which means that 28 is a perfect number.
A number n is called deficient if the sum of its proper divisors is less than n and it is called abundant if this sum exceeds n.
As 12 is the smallest abundant number, 1 + 2 + 3 + 4 + 6 = 16, the smallest number that can be written as the sum of two abundant numbers is 24. By mathematical analysis, it can be shown that all integers greater than 28123 can be written as the sum of two abundant numbers. However, this upper limit cannot be reduced any further by analysis >even though it is known that the greatest number that cannot be expressed as the sum of two abundant numbers is less than this limit.
Find the sum of all the positive integers which cannot be written as the sum of two abundant numbers.
This is my code:
import math
def getDivisors(num):
n = math.ceil(math.sqrt(num))
total = 1
divisor = 2
while (divisor < n):
if (num%divisor == 0):
total += divisor
total += num//divisor
divisor+=1
return total
def isAbundant(num):
if (getDivisors(num) > num):
return True
else:
return False
abundentNums = []
for x in range (0,28124):
if (isAbundant(x)):
abundentNums.append(x)
del abundentNums[0]
sums = [0]*28124
for x in range (0, len(abundentNums)):
for y in range (x, len(abundentNums)):
sumOf2AbundantNums = abundentNums[x]+abundentNums[y]
if (sumOf2AbundantNums<= 28123):
if (sums[sumOf2AbundantNums] == 0):
sums[sumOf2AbundantNums] = sumOf2AbundantNums
total = 0
for x in range (1,len(sums)):
if (sums[x] == 0):
total +=x
print('\n', total)
The total value I get is 4190404. The correct answer is 4179871.I have spent an hour looking at my code, but I am unable to find the error. What should I change to correct the error? My answer is close. Thanks in advance
PS. I am new to python. Run time is 25s any optimisations will be useful as well.