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.
就是获得一个整数的各个位的值，以及求整数的长度，负数直接排除。
- bool isPalindrome(int x) {
- if(x<0)
- return false;
- int t=x;
- int length=0;
- while(t){
- t=t/10;
- length++;
- }
- for(int i=0;i<length/2;i++){
- if(f(x,i)!=f(x,length-1-i))
- return false;
- }
- return true;
- }
- int f(int x, int n){
- for(int i=0;i<n;i++){
- x=x/10;
- }
- return x%10;
- }
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