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9. Palindrome Number 👍

  • Time: $O(\log x)$
  • Space: $O(1)$
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class Solution {
 public:
  bool isPalindrome(int x) {
    if (x < 0)
      return false;

    long reversed = 0;
    int y = x;

    while (y > 0) {
      reversed = reversed * 10 + y % 10;
      y /= 10;
    }

    return reversed == x;
  }
};

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class Solution {
  public boolean isPalindrome(int x) {
    if (x < 0)
      return false;

    long reversed = 0;
    int y = x;

    while (y > 0) {
      reversed = reversed * 10 + y % 10;
      y /= 10;
    }

    return reversed == x;
  }
}

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class Solution:
  def isPalindrome(self, x: int) -> bool:
    if x < 0:
      return False

    rev = 0
    y = x

    while y:
      rev = rev * 10 + y % 10
      y //= 10

    return rev == x