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leetcode——7 Reverse Integer(附有溢出整数翻转的实现)

时间:2015-06-19 10:27:39      阅读:155      评论:0      收藏:0      [点我收藏+]
Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

Have you thought about this?
Here are some good questions to ask before coding. Bonus points for you if you have already thought through this!

If the integer‘s last digit is 0, what should the output be? ie, cases such as 10, 100.

Did you notice that the reversed integer might overflow? Assume the input is a 32-bit integer, then the reverse of 1000000003 overflows. How should you handle such cases?

For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

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解题思路:
(1)从给定数n的低位进行分离:int s=n%10;
(2)分离出的数,进行等效翻转操作:sum=sum*10+s; 为了防止溢出操作,将sum的类型定义为:long
(3)n/=10;继续循环操作
(4)检查是否溢出:如果sum>Integer.MAX_VALUE||sum<Integer.MIN_VALUE,则已经溢出,返回为0;如果没有溢出将sum强制类型转换为int即可


代码如下:

	public static int reverse(int n)
	{
		//输出结果定义为long
		long sum=0;
		while (n!=0)
		{
			int s=n%10;
			sum=sum*10+s;
			n=n/10;
		}
		
		//防止溢出操作
		if (sum>Integer.MAX_VALUE||sum<Integer.MIN_VALUE)
		{
			return 0;
		}
		return (int)sum;
	}

leetcode——7 Reverse Integer(附有溢出整数翻转的实现)

原文:http://blog.csdn.net/zzc8265020/article/details/46558289

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