#ProjectEuler/ProjectEulerPython/Problems/Problem37.py #Matthew Ellison # Created: 07-01-21 #Modified: 07-01-21 #Find the sum of the only eleven primes that are both truncatable from left to right and right to left (2, 3, 5, and 7 are not counted). #Unless otherwise listed, all of my non-standard imports can be gotten from my pyClasses repository at https://bitbucket.org/Mattrixwv/pyClasses """ Copyright (C) 2021 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 Problems.Problem import Problem import NumberAlgorithms class Problem37(Problem): #Variables __last_prime_before_check = 7 #The last prime before 11 since single digit primes aren't checked #Functions #Constructor def __init__(self) -> None: super().__init__("Find the sum of the only eleven primes that are both truncatable from left to right and right to left (2, 3, 5, and 7 are not counted).") self.truncPrimes = [] #All numbers that are truncatable primes self.sumOfTruncPrimes = 0 #The sum of all elements in truncPrimes #Operational functions #Solve the problem def solve(self) -> None: #If the problem has already been solved do nothing and end the function if(self.solved): return #Start the timer self.timer.start() #Create the sieve and get the first prime number sieve = NumberAlgorithms.primeGenerator() currentPrime = next(sieve) #Loop through the sieve until you get to __last_prime_before_check while(currentPrime < self.__last_prime_before_check): currentPrime = next(sieve) #Loop until truncPrimes contains 11 elements while(len(self.truncPrimes) < 11): isTruncPrime = True #Get the next prime currentPrime = next(sieve) #Convert the prime to a string primeString = str(currentPrime) #If the string contains an even digit move to the next prime for strLoc in range(0, len(primeString)): #Allow 2 to be the first digit if((strLoc == 0) and (primeString[strLoc] == '2')): continue if((primeString[strLoc] == '0') or (primeString[strLoc] == '2') or (primeString[strLoc] == '4') or (primeString[strLoc] == '6') or (primeString[strLoc] == '8')): isTruncPrime = False break #Start removing digits from the left and see if the number stays prime if(isTruncPrime): for truncLoc in range(1, len(primeString)): #Create a substring of the prime, removing the needed digits from the left primeSubstring = primeString[truncLoc::] #Convert the string to an int and see if the number is still prime newPrime = int(primeSubstring) if(not NumberAlgorithms.isPrime(newPrime)): isTruncPrime = False break #Start removing digits from the right and see if the number stays prime if(isTruncPrime): for truncLoc in range(1, len(primeString)): #Create a substring of the prime, removing the needed digits from the right primeSubstring = primeString[0:len(primeString) - truncLoc] #Convert the string to an int and see if the number is still prime newPrime = int(primeSubstring) if(not NumberAlgorithms.isPrime(newPrime)): isTruncPrime = False break #If the number remained prime through all operations add it to the vector if(isTruncPrime): self.truncPrimes.append(currentPrime) #End the loop if we have collected enough primes if(len(self.truncPrimes) == 11): break #Get the sum of all elements in the truncPrimes vector self.sumOfTruncPrimes = sum(self.truncPrimes) #Stop the timer self.timer.stop() #Throw a flag to show the problem is solved self.solved = True #Reset the problem so it can be run again def reset(self) -> None: super().reset() self.truncPrimes = [] self.sumOfTruncPrimes = 0 #Gets #Returns a string with the solution to the problem def getResult(self) -> str: self.solvedCheck("result") return f"The sum of all left and right truncatable primes is {self.sumOfTruncPrimes}" #Returns the list of primes that can be truncated def getTruncatablePrimes(self) -> list: self.solvedCheck("list of truncatable primes") return self.truncPrimes #Returns the sum of all elements in truncPrimes def getSumOfPrimes(self) -> int: self.solvedCheck("sum of truncatable primes") return self.sumOfTruncPrimes """ Results: The sum of all left and right truncatable primes is 748317 It took an average of 224.657 milliseconds to run this problem through 100 iterations """