Palindrome Number
Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.
Example
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:
Could you solve it without converting the integer to a string?
Note
数位分离+反转
计算反转一半和半段是不是相等
x是前半段
r是反转的后半段 x == r / 10,x == r 对应奇数和偶数(奇数中间位不判断)
Code
public boolean isPalindrome(int x) {
if( x < 0 || (x != 0 && x % 10 == 0)) return false;
int num = x;
int r = 0;
while (x > r) {
r = r * 10 + x % 10;
x /= 10;
}
return (x == r || x == r / 10);
}
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