#ProjectEuler/Python/Problem23.py #Matthew Ellison # Created: 03-22-19 #Modified: 03-28-19 #Find the sum of all the positive integers which cannot be written as the sum of two abundant numbers #All of my imports can be gotten from my pyClasses repository at https://bitbucket.org/Mattrixwv/pyClasses """ Copyright (C) 2019 Matthew Ellison This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this program. If not, see . """ from Stopwatch import Stopwatch import Algorithms __maxNum = 28123 #A function that returns true if num can be created by adding two elements from abund and false if it cannot def isSum(abund: list, num: int) -> bool: sumOfNums = 0 #Pick a number for the first part of the sum for firstNum in range(0, len(abund)): #Pick a number for the second part of the sum for secondNum in range(0, len(abund)): sumOfNums = abund[firstNum] + abund[secondNum] if(sumOfNums == num): return True elif(sumOfNums > num): break #If you have run through the entire list and did not find a sum then it is false return False def Problem23(): #Setup the variables divisorSums = [] #Make sure every element has a 0 in it's location for cnt in range(0, __maxNum): divisorSums.append(0) #Get the sum of the divisors of all numbers < __maxNum for cnt in range(1, __maxNum): div = Algorithms.getDivisors(cnt) if(len(div) > 1): div.remove(div[len(div) - 1]) divisorSums[cnt] = sum(div) #Get the abundant numbers abund = [] for cnt in range(0, len(divisorSums)): if(divisorSums[cnt] > cnt): abund.append(cnt) #Check if each number can be the sum of 2 abundant numbers and add to the sum if no sumOfNums = 0 for cnt in range(1, __maxNum): if(not isSum(abund, cnt)): sumOfNums += cnt #Print the results print("The answer is " + str(sumOfNums)) if __name__ == "__main__": timer = Stopwatch() timer.start() Problem23() timer.stop() print("It took " + timer.getString() + " to run this algorithm") """ Results: The answer is 4179871 It took 27.738 minutes to run this algorithm """