Palindrome chain length ( 5 kyu )

Palindrome chain length ( 5 kyu )

문제

Number is a palindrome if it is equal to the number with digits in reversed order. For example, 5, 44, 171, 4884 are palindromes and 43, 194, 4773 are not palindromes.

Write a method palindrome_chain_length which takes a positive number and returns the number of special steps needed to obtain a palindrome. The special step is: “reverse the digits, and add to the original number”. If the resulting number is not a palindrome, repeat the procedure with the sum until the resulting number is a palindrome.

If the input number is already a palindrome, the number of steps is 0.

Input will always be a positive integer.

For example, start with 87:

87 + 78 = 165; 165 + 561 = 726; 726 + 627 = 1353; 1353 + 3531 = 4884

4884 is a palindrome and we needed 4 steps to obtain it, so palindrome_chain_length(87) == 4

해당 숫자와 뒤집은 수의 합이 팰린드롬수가 될 때까지 몇번의 연산을 해야하는지 구하는 문제

풀이

var palindromeChainLength = function(n) {
  let count = 0;
  while ( n.toString() !== n.toString().split('').reverse().join('') ) {
    n = n + parseInt(n.toString().split('').reverse().join(''))
    count++
  }
  return count;
};

그냥 n이 팰린드롬 수가 될 때까지 횟수 반복, 카운트

왜 5 kyu 인가..

다른 사람의 풀이

var palindromeChainLength  = function(n) {  
  var x = parseInt( (""+n).split('').reverse().join('') );
  if(n != x){
    return 1 + palindromeChainLength (n + x);
  }
  return 0;
};

재귀로 푸는 방법