PalindromeNumbers@leetcode

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

click to show spoilers.

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.

Have you been asked this question in an interview? 

Discuss

Since no extra space is allowed, then we can't convert it to anything else. Now we can use two integers to record the head and tail numbers of the given integer, then compare the head and tail one by one.