LeetCode Palindrome Number

最新推荐文章于 2020-08-18 15:23:01 发布

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本文介绍了一种不使用额外空间判断整数是否为回文的方法。通过将整数逆序并与原数比较来实现，特别注意了负数和溢出的情况。

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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.

挺简单的题目，把该串逆置然后对比原来的看是否相等，相等就输出true；

代码：

public class Solution {
    public boolean isPalindrome(int x) {
       if(x<0)
	    return false;
	   if(x==0)
	    return true;
	   int cur=x;
	   int rev=0;
	   while(cur!=0)
	   {
	       rev=rev*10+cur%10; //逆序
	       cur/=10;
	   }
	   if(x==rev)
	       return true;
	       else
	       return false;
    }
}