leetcode [#7]

目录

• 1. 题目
• 2. 解决方案
• 3. 注意事项

题目

Reverse digits of an integer.

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

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解决方案

public class Solution {
    public int reverse(int x) {
        String s = String.valueOf(x);
        if(x < 0) s = s.substring(1, s.length());
        StringBuilder builder = new StringBuilder();
        for(int i = s.length() - 1; i>=0; i--) builder.append(s.charAt(i));
        if((x > 0 && builder.length() == 10 && builder.toString().compareTo("2147483647") > 0) || (x < 0 && builder.length() == 10 && builder.toString().compareTo("2147483648") > 0)) return 0;
        int res = Integer.valueOf(builder.toString());
        return x > 0 ? res : 0 - res;
    }
}

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注意事项

1. 转换为字符串考虑，注意正负情况和边界溢出情况。