LeetCode 9. Palindrome Number

原题链接在这里：https://leetcode.com/problems/palindrome-number/

题目：Determine whether an integer is a palindrome. Do this without extra space.

题解：

div 表示能走到x的最高位. x/div就是x的最高位.

Note: In case of overflow, when calculating limit, while loop needs limit <= x/10, but not limit * 10 < x. 

Since limit * 10 may be overflow already.

Time Complexity: O(digit), digit代表x共有多少位.

Space: O(1).

AC Java:

class Solution {
    public boolean isPalindrome(int x) {
        if(x < 0){
            return false;
        }
        
        int limit = 1;
        while(limit <= x / 10){
            limit *= 10;
        }
        
        while(x > 0){
            if(x / limit != x % 10){
                return false;
            }
            
            x = (x % limit) / 10;
            limit /= 100;
        }
        
        return true;
    }
}

类似Palindrome Linked List.