[刷题防痴呆] 0482 - 密钥格式化 (License Ke

题目地址

https://leetcode.com/problems/license-key-formatting/

题目描述

482. License Key Formatting

You are given a license key represented as a string s that consists of only alphanumeric characters and dashes. The string is separated into n + 1 groups by n dashes. You are also given an integer k.

We want to reformat the string s such that each group contains exactly k characters, except for the first group, which could be shorter than k but still must contain at least one character. Furthermore, there must be a dash inserted between two groups, and you should convert all lowercase letters to uppercase.

Return the reformatted license key.

 

Example 1:

Input: s = "5F3Z-2e-9-w", k = 4
Output: "5F3Z-2E9W"
Explanation: The string s has been split into two parts, each part has 4 characters.
Note that the two extra dashes are not needed and can be removed.
Example 2:

Input: s = "2-5g-3-J", k = 2
Output: "2-5G-3J"
Explanation: The string s has been split into three parts, each part has 2 characters except the first part as it could be shorter as mentioned above.

思路

• replace掉所有的"-", 并toUpperCase.
• 如果当前string的len小于k, 直接返回.
• 如果len可以被k整除, 则正常按照每k个append.
• 否则, 需要先取余, 把小于k的个数个char加入stringbuffer中, 之后正常按每k个append即可.

关键点

• 注意, 删除掉最后一位多append的"-".

代码

• 语言支持：Java

class Solution {
    public String licenseKeyFormatting(String s, int k) {
        s = s.replace("-", "");
        s = s.toUpperCase();
        StringBuffer sb = new StringBuffer();
        int len = s.length();
        if (len < k) {
            return s;
        }

        int index = 0;
        if (len % k == 0) {
            sb.append(s.substring(0, k));
            sb.append("-");
            index = k;
        } else {
            int reminder = len % k;
            sb.append(s.substring(0, reminder));
            sb.append("-");
            index = reminder;
        }

        while (index < len) {
            sb.append(s.substring(index, index + k));
            index += k;
            sb.append("-");
        }
        sb.deleteCharAt(sb.length() - 1);

        return sb.toString();
    }
}