題目描述

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 store integers within the 32-bit signed integer range: [−231, 231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

AC程式碼

class Solution {
    public int reverse(int x) {
        int negative = 1;
        if(x < 0) {
        	negative = -1;
            x = x * -1;
        }
        char[] charIntMax = String.valueOf(Integer.MAX_VALUE).toCharArray();
        char[] chars = String.valueOf(x).trim().toCharArray()
 
;
        int low = 0, high = chars.length - 1;
        while(low < high){
            char tmp = chars[low];
            chars[low] = chars[high];
            chars[high] = tmp;
            low++;
            high--;
        }
        
        if(chars.length < charIntMax.length) return Integer.
 
valueOf(new String(chars)) * negative;
        low = 0;
        high = charIntMax.length - 1;
        
        while(low <= high){
        	if(charIntMax[low] > chars[low]) return Integer.valueOf(new String(chars)) * negative;
        	if(charIntMax[low] < chars[low]) return 0;
            low++;
        }
        return 0;
    }
}