【LeetCode & 剑指offer 刷题笔记】目录（持续更新中...）
Reverse Integer
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:
Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231, 231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.
#include<climits>
/*static int x = []() {
std::ios::sync_with_stdio(false);
cin.tie(NULL);
return 0;
}();*/
class Solution
{
public:
int reverse(int x)
{
//int反转后最大也不超过用33位（1000……）。
long long res = 0;//保证即使在32位系统中变量也为64位，比int位宽大
long long t = x; //中间变量
t = t>0? t:-t; //取绝对值
while(t>0)
{
res = res*10 + t%10;
t /= 10; //t除以10再模10就能依次获得各位数字
}
//判断符号
if(x>0)//处理溢出情况
{
if(res>INT_MAX) return 0;
else return res;
}
else
{
res = -res;
if(res<INT_MIN) return 0;
else return res;
}
}
};