9. Palindrome Number
Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
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?
Solution
class Solution {
public:
bool isPalindrome(int x) {
int val = 0;
int origin = x;
if (x < 0) return false;
while( x != 0)
{
int pop = x % 10;
x /= 10;
if ( val > INT_MAX/10 || (val == INT_MAX/10 && pop > 7)) return false;
val = val * 10 + pop;
}
if (val == origin) return true;
else return false;
}
};
解题思路
先把整型数反转,在不溢出的情况下判断回文与原文是否相等。