leetcode_26题——Reverse Integer（int型的表示范围）

#include<iostream>
#include<math.h>
using namespace std;

int reverse(int x) 
{
	if(x>=0)
	{
		int a=x;
		int b=a/10;
		int c=a%10;
		int last_result=c;
		while(b!=0)
		{
			if(last_result>2147483647/10)
				return 0;
			last_result*=10;
			c=b%10;
			b=b/10;
			if(last_result>2147483647-c)
				return 0;
			last_result+=c;
		}
		return last_result;
	}
	else
	{
		int a=abs(x);
		int b=a/10;
		int c=a%10;
		int last_result=c;
		while(b!=0)
		{
			if(last_result>2147483647/10)//(2^31-1)/10
				return 0;
			last_result*=10;
			c=b%10;
			b=b/10;
			if(last_result>2147483647-c)//2^31-1-c
				return 0;
			last_result+=c;
		}
		return -last_result;
	}
}
int main()
{
	//int x=1534236469;
	//int x=-2147483648;
	//int x=1563847412;
	int x=-2147483412;
	cout<<reverse(x)<<endl;
	/*
	long int a=964632435;
	long int c=9646324351;
	long int b=a*10;
	cout<<a<<‘ ‘<<b<<‘ ‘<<c<<endl;*/
}