leetcode Palindrome Number 2.4 难度系数2

最新推荐文章于 2023-04-15 01:48:20 发布

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最新推荐文章于 2023-04-15 01:48:20 发布

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本文介绍了一种不使用额外空间来判断整数是否为回文数的方法，包括如何处理负数情况及反转整数可能引发的溢出问题。

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Question:

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.

 public boolean isPalindrome(int x) {
    	if (x<0) {
			return false;
		}
    	if (x==0) {
    		return true;
		}
    	int reverseX = reverse(x);
    	return x==reverseX?true:false;
    }
    private int reverse(int x) {
        int result = 0;
        while(x!=0){
        	result = result *10+x%10;
        	x/=10;
        }
        return result;
    }