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  1. Practice
  2. Algorithms
  3. Implementation
  4. Beautiful Days at the Movies
  5. Discussions

Beautiful Days at the Movies

  • TedYav + 3 comments

    using functional operations :)

    i,j,k = map(int,input().strip().split())
def reversed(n): return int(str(n)[::-1])
def is_beautiful(n): return abs(n - reversed(n)) % k == 0
print(len(list(filter(is_beautiful, range(i,j+1)))))

    or two line, unintelligible version :p

    i,j,k = map(int,input().strip().split())
print(len(list(filter(lambda n: abs(n - int(str(n)[::-1])) % k==0, range(i,j+1)))))

    • nuhman + 1 comment

      Which course/book are you following on python?

      • TedYav + 0 comments

        Learned Python as part of Discrete Math course and mostly self taught since :)

    • askarovdaulet + 1 comment

      filter and lambda together look too confusing. Generator expressions would be much better here. Also, you don't need absolute value. Mod operation should work on negative numbers. Like this:

      i,j,k = map(int,input().strip().split())
print(sum((x-int(str(x)[::-1]))%k==0 for x in range(i,j+1)))

      • TedYav + 0 comments

        Good solution! You're right about negative mod. Wasn't thinking about that. And I'm not super familiar with generator expressions. Your solution has inspired me to look into them more.

    • boertjie_seun + 2 comments

      This was my solution in Swift

      import Foundation

// Complete the beautifulDays function below.
func beautifulDays(i: Int, j: Int, k: Int) -> Int {
    var count = 0

    for value in i...j {
        var r = value
        var q = 0
        while r > 0 {
            q = q * 10 + r % 10
            r /= 10
        }
        abs(value - q) % k == 0 ? count += 1 : ()
    }
    return count
}

      • codded + 3 comments

        i did the same ,but iam getting runtime error

        • maitabar_sultan1 + 1 comment

          swift is slow

          • maitabar_sultan1 + 0 comments

            swift not for server side, and fast work

        • the_cyberMuggle + 0 comments
          [deleted]

        • the_cyberMuggle + 0 comments

          I think your code was wrong. I think you lost variable i's value, because in while loop it changes its value to 0.

          I think this has to work fine.

          int count = 0; for (; i <= j; i++) { int num = i; int revNum = 0; while (num > 0) { revNum = 10 * revNum + num % 10; num /= 10; } if (Math.abs(i - revNum) % k == 0) count++; } return count;

      • quick_dudley + 0 comments

        Nearly identical to my rust solution except I had the loop to reverse the number as a separate function.