LeetCode 7. Reverse Integer（c语言版）

题目：

   

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.

题解：

    因为还不太会用c++和java，所以用c语言写的，题意很好理解，题也很简单，但需要注意溢出的问题，输入没有溢出，但翻转可能有溢出。

代码：

int reverse(int x) {
    long long y=0;     //用longlong为了看是否有溢出
    if(x>=pow(2,31)-1||x<=-pow(2,31)) return 0;
    while(x!=0)
    {
        int v=x%10;
        y=y*10+v;
        if(y>pow(2,31)-1||y<-pow(2,31)) return 0;
        x/=10;
    }
    int n=y;
    return n;
}