# Lucky Numbers

# Lucky Numbers

+ 6 comments why 23 in between 21 and 25 is not lucky number,

as we are getting digit sum 5, and sum of square of digits are 13.

+ 0 comments **Here is Lucky Numbers problem solution in Python Java C++ and C programming**- https://programs.programmingoneonone.com/2021/07/hackerrank-lucky-numbers-problem-soluton.html

+ 0 comments **Here is Lucky Numbers problem solution in Python Java C++ and C programming**- https://programs.programmingoneonone.com/2021/07/hackerrank-lucky-numbers-problem-soluton.html

+ 0 comments This problem is obscenely difficult, and I spent days researching just to get fairly close to the correct solution, then I spent days more tweaking my approach to conform to the extra constraints created by the problem itself. In order to complete this in a reasonable time, you have to dig into number theory by realizing that, at least for a=1 to b=(some number of consecutive 9's), the problem resembles a permutation problem (since we take the sums/squares of these numbers, the question becomes 'how many combinations of k digits result in a prime number between 1 and 999999999999999999 when (summed) or (squared)?' and 'how can you exclude permutations that are less than a, and greater than b?'

Honestly, I'm still not even finished trying to make the damn thing work, I just know the approach WILL work, once I've debugged everything.

+ 1 comment # can anyone let me know how i can optimize it further

# !/bin/python3

import math import os import random import re import sys

#

# Complete the 'luckyNumbers' function below.

#

# The function is expected to return a LONG_INTEGER.

# The function accepts following parameters:

# 1. LONG_INTEGER a

# 2. LONG_INTEGER b

#

def luckyNumbers(a, b): # Write your code here temp = 0 total = 0

`for i in range(a,b+1): temp = i totalsum = 0 totalsumsq = 0 while temp != 0: digit = temp % 10 temp = temp // 10 totalsum = totalsum + digit totalsumsq = totalsumsq + (digit**2) def isprime(n): if n > 1: for k in range(2,n): if (n % k) == 0: return False return True else: return False isprime(totalsum) isprime(totalsumsq) if isprime(totalsum) and isprime(totalsumsq): total = total + 1 return total`

if

**name**== '**main**': fptr = open(os.environ['OUTPUT_PATH'], 'w')`t = int(input().strip()) for t_itr in range(t): first_multiple_input = input().rstrip().split() a = int(first_multiple_input[0]) b = int(first_multiple_input[1]) result = luckyNumbers(a, b) fptr.write(str(result) + '\n') fptr.close()`

Sort 70 Discussions, By:

Please Login in order to post a comment