9. Palindrome Number

发表于 | 分类于 ， | 阅读次数:

Total Accepted: 106331
Total Submissions: 345763
Difficulty: Easy

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

click to show spoilers.

Some hints:

Could negative integers be palindromes? (ie, -1)

If you are thinking of converting the integer to string, note the restriction of using extra space.

You could also try reversing an integer. However, if you have solved the problem “Reverse Integer”, you know that the reversed integer might overflow. How would you handle such case?

There is a more generic way of solving this problem.

Java:

1
2
3
4
5
6
7
8
9
10
11
12
13
public class Solution {
    public boolean isPalindrome(int x) {
        if (x < 0)
            return false;
        int y = 0, x1 = 1;
        while (x / x1 != 0) {
            y = y * 10 + x % 10;
            x /= 10;
            x1 *= 10;
        }
        return y < 10 * x ? y == x : y / 10 == x;
    }
}

打个小广告

欢迎加入我的小专栏「基你太美」一起学习。