-
Notifications
You must be signed in to change notification settings - Fork 0
/
9. Palindrome Number
49 lines (34 loc) · 1 KB
/
9. Palindrome Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
/***************************************************
Given an integer x, return true if x is a
palindrome
, and false otherwise.
Example 1:
Input: x = 121
Output: true
Explanation: 121 reads as 121 from left to right and from right to left.
Example 2:
Input: x = -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: x = 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.
Constraints:
-231 <= x <= 231 - 1
Follow up: Could you solve it without converting the integer to a string?
************************************************
class Solution {
public:
bool isPalindrome(int n) {
if(n < 0 || (n % 10 == 0 && n != 0)) {
return false;
}
int revnum = 0;
while(n > revnum) {
revnum = (revnum * 10) + (n % 10);
n = n / 10;
}
return n == revnum || n == revnum / 10;
}
};