LeetCode 007 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.

class Solution { public int reverse(int x) { boolean flag = false; if(x < 0) { flag = true; x = -x; } long temp = 0; // 注意这里需要long while(x != 0) { temp = temp * 10 + x % 10; x /= 10; } if(flag) temp = -temp; if(temp <= Integer.MAX_VALUE && temp >= Integer.MIN_VALUE) return (int)temp; else return 0; } }