Leetcode7——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 hold integers within the 32-bit signed integer range. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

代码：

class Solution {
public int reverse(int x) {
List<Integer> arr=new ArrayList<>();
int flag=1;
if(x<0){
x=-x;
flag=-1;
}
while(x>0){
arr.add(x%10);
x/=10;
}
int len=arr.size();
int y=0;
for(int i=0; i<len;i++){
y+=arr.get(i)*Math.pow(10,len-i-1);
}
if(y>=2147483647){
return 0;
}
else{
return y*flag;
}
}
}