[LeetCode]-Palindrome Number 判斷整數迴文

Palindrome Number

 

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.

思路：獲取integer的逆向值，用取餘的辦法。對於負數，直接判斷不迴文。對於整形逆轉後溢出情況，考慮轉換爲unsigned int。

class Solution {
public:
    bool isPalindrome(int x) {
        if(x<0)return false;
        unsigned int b=0;
        unsigned int a=x;
        while(a){
            b*=10;
            b+=a%10;
            a=a/10;
        }
        if(b==x)return true;
        else
            return false;
    }
};