LeetCode - Palindrome Number | Darren's Blog

Determine whether an integer is a palindrome. Do this without extra space. Assume that a negative integer is not a palindrome.

public boolean isPalindrome(int x) {

        if (x < 0)      // Negative numbers are assumed to be non-palindromic

            return false;

        // The smallest integer that has the same number of digits with x

        // Used to get the leftmost digit

        int oneZeros = 1;

        while (x / oneZeros >= 10)

            oneZeros *= 10;

        // Compare the digits at both ends

        while (x != 0) {

            int leftmost = x / oneZeros;

            int rightmost = x % 10;

            if (leftmost != rightmost)

                return false;

            x = (x % oneZeros) / 10;     // Chop the leftmost and rightmost digits

            oneZeros /= 100;             // Update oneZeros as two digits are chopped

        }

        return true;

    }

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