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();
}
}
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