9. Palindrome number

9. A palindrome

Simple even if we simulate a walk, store each number walk is not a problem, because the comparison is only int.

But this problem provides a palindrome idea, or good.

Use the size of the front and back to see if it’s symmetrical.

    public boolean isPalindrome(int x) {
        if (x < 0 || (x % 10= =0&& x ! =0)) return false;
        int rev = 0;
        while (x > rev) {
            rev = rev * 10 + x % 10;
            x = x / 10;
        }
        return x == rev || rev / 10 == x;
    }
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