Determine whether an integer is a palindrome. Do this without extra space.

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Some hints:
Could negative integers be palindromes? (ie, -1)

If you are thinking of converting the integer to string, note the restriction of using extra space.

You could also try reversing an integer. However, if you have solved the problem "Reverse Integer", you know that the reversed integer might overflow. How would you handle such case?

There is a more generic way of solving this problem.

```bool isPalindrome(int x)
{
if(x < 0)
return false;

long long val = 0;
int temp = x;
while(x)
{
val = val *10 + x %10;
x = x / 10;
}

if(val > INT_MAX || val < INT_MIN || (val != temp))
return false;

return true;

}
```

2021.08.24更新

``````class Solution {
public:
bool isPalindrome(int x) {
if(x < 0 || (x!=0 && x%10==0)) return false;

int sum = 0;
while(x > sum)
{
sum = sum * 10 + x % 10;
x = x/10;
}

return (x == sum) || (x == sum/10);
}
};``````

``````Runtime: 0 ms, faster than 100.00% of C++ online submissions for Palindrome Number.
Memory Usage: 5.9 MB, less than 72.80% of C++ online submissions for Palindrome Number.``````

``````class Solution {
public:
bool isPalindrome(int x) {
string str = to_string(x);
int n = str.size();
for(int i = 0;i < n/2;i++)
{
if(str[i] != str[n - i - 1])
return false;
}
return true;

}
};``````

``````执行用时：28 ms, 在所有 C++ 提交中击败了11.22%的用户