Palindrome Number ——解題筆記

    【題目】 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.

    解法：把int類型的數逐個分解，所有元素放在一個vector中，然後判斷這個vector是否是左右對稱的。

    注意：vector中push_back添加元素的用法；vector可以直接用下表取數。

    代碼如下：

class Solution {
public:
    bool isPalindrome(int x) {
        if(x < 0)
            return false;
            
        vector<int> nums;
        while(x)
        {
            nums.push_back(x%10);
            x /= 10;
        }
        
        int len = nums.size();
        for(int i = 0; i < len/2; i++)
        {
            if(nums[i] != nums[len - 1 - i])  % 下標要注意
                return false;
        }
        return true;
    }
};