7. Reverse Integer

Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

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Note:
The input is assumed to be a 32-bit signed integer. Your function should return 0 when the reversed integer overflows.

 

 

 难点在于溢出的判断，在计算下一位数之前，看res如果比最大值的10分之一大，或者比最小值的十分之一小的话，则下一次计算会溢出。

 

 

public class Solution {
    public int reverse(int x) {
        int res=0;
        while(x!=0){
            
            if(res>Integer.MAX_VALUE/10||res<Integer.MIN_VALUE/10){
                return 0;
            }
            res=res*10+x%10;
            x/=10;
        }
        return res;
    }
}