ReverseInteger

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

Example 1:

Input: 123
Output: 321

Example 2:

Input: -123
Output: -321

Example 3:

Input: 120
Output: 21

Note:

function returns 0 when the reversed integer overflows.

#include <iostream>
#include <limits.h>
using namespace std;
int reverse(int x)
{
	long long sum = 0;
	if( x/10 == 0) {
		return x;
	}
	else {
		long long m = (x%10);
		long long n = x/10;
		while(n /= 10)
			m *= 10;
		sum = m + reverse(x/10);
	}
	return (sum < INT_MIN || sum > INT_MAX) ? 0 :sum;
}

int main()
{
	cout<<reverse(1234)<<endl;
	return 0;
}

Output: 4321

参考自:

1. https://leetcode.com/problems/reverse-integer/discuss/4057/
2. http://bbs.csdn.net/topics/390741045?page=1