Determine
whether an integer is a palindrome. Do this without extra space.
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.
Pasted
from <http://leetcode.com/onlinejudge>
class Solution {
public:
bool isPalindrome(int x) {
if (x < 0)
return false;
long long absx = abs((long long)x);
int k=1;
int x1 = absx;
while(x1 >= 10)
{
x1 = x1 / 10;
k = k * 10;
}
x1 = absx;
while(x1)
{
if (x1 / k != x1 %10)
return false;
x1 = (x1 % k) / 10;
k = k / 100;
}
return true;
}
};
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