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.
Solution:
1) If x is negative, return false;
2) Create x’s inverse. Be careful with overflow!
3) Check if inverse == x;
class Solution {
public:
bool isPalindrome(int x) {
if(x<0) return false;
int z = x;
int y = 0;
while(x){
if(y < (INT_MAX-(x%10))/10){
y *= 10;
y += x%10;
}
else{
return false;
}
x /= 10;
}
return z==y;
}
};