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.

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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;
        }
    }
}