【leetcode】9. palindrome number

1.题目描述

Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.

判断一个整数是否是回文数。回文数是指正序(从左向右)和倒序(从右向左)读都是一样的整数。

Example 1:

Input: 121
Output: true

Example 2:

Input: -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

Example 3:

Input: 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

Follow up:

Coud you solve it without converting the integer to a string?

你能不将整数转为字符串来解决这个问题吗?

2.Solutions

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public static boolean (int x) {
if(x < 0) return false;
int y = x;
int res = 0;
while(y != 0) {
res = res * 10 + y % 10;
y /= 10;
}
return x == res;
}

(完)