Q7：Reverse Integer

7. Reverse Integer

官方的链接：7. Reverse Integer

Description ：

Given a 32-bit signed integer, reverse digits of an integer.

Example1:

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Input: 123

Output: 321

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 Example2:

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 Input: -123

Output: -321

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 Example3:

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 Input: 120

Output: 21

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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.

问题描述

 反转32位的数字

思路

 上一次的模*10 + 这一次的模。中间判断是否有溢出

注意：last_mod * 10 + this_mod，而x /= 10

[github-here]

public class Q7_ReverseInteger {
    public int reverse(int x) {
        int revResult = 0;
        while (0 != x){
            int newResult = revResult * 10 + x % 10;
            //judge whether it overflows
            if (newResult / 10 != revResult) {
                return 0;
            }
            revResult = newResult;
            x /= 10;
        }
        return revResult;
    }
}