README.md

Reverse Integer

Description

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.

思路

使用长整型保存结果。依次模 10 得到最右边一位。

实现代码

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