【leetcode】7. Reverse Integer（C）

Description：

Given a 32-bit signed integer, reverse digits of an integer.

Example1:

Input: 123
Output: 321

Example2:

Input: -123
Output: -321

Example3:

Input: 120
Output: 21

[ 题目链接 ]

提交代码：

int reverse(int x) {
 //int正数最大2147483647 负数最大-2147483648
	int tmp=x,flag;
	int i=0,x_reverse=0,len=0;
	int nums[10];

	//是个正数
	if (x > 0)
	{
		//将这个数存到一个数组里面
		while (tmp != 0)
		{
			nums[i++] = tmp % 10;
			tmp /= 10;
			len++;
		}

		//看有没有越界
		if (len == 10)
		{
			if (nums[0] > 2)	return 0;
			else if (nums[0] == 2)
			{
				tmp = 0;
				for (i = 1; i <len; i++)
					tmp = tmp * 10 + nums[i];

				if (tmp > 147483647)	return 0;
			}
		}
		tmp = 0;
		for (i = 0; i <len; i++)
			tmp = tmp * 10 + nums[i];
		return tmp;
	}

	//是个负数
	else
	{
		while (tmp != 0)
		{
			nums[i++] = -1*(tmp % 10);
			tmp /= 10;
			len++;
		}

		//看有没有越界
		if (len == 10)
		{
			if (nums[0] > 2)	return 0;
			else if (nums[0] == 2)
			{
				tmp = 0;
				for (i = 1; i <len; i++)
					tmp = tmp * 10 + nums[i];

				if (tmp > 147483648)	return 0;
			}
		}
		tmp = 0;
		for (i = 0; i <len; i++)
			tmp = tmp * 10 + nums[i];
		return -1 * tmp;
	}
}

运行结果：