g1301_1400.s1370_increasing_decreasing_string.readme.md Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of leetcode-in-java21 Show documentation
Show all versions of leetcode-in-java21 Show documentation
Java-based LeetCode algorithm problem solutions, regularly updated
1370\. Increasing Decreasing String
Easy
You are given a string `s`. Reorder the string using the following algorithm:
1. Pick the **smallest** character from `s` and **append** it to the result.
2. Pick the **smallest** character from `s` which is greater than the last appended character to the result and **append** it.
3. Repeat step 2 until you cannot pick more characters.
4. Pick the **largest** character from `s` and **append** it to the result.
5. Pick the **largest** character from `s` which is smaller than the last appended character to the result and **append** it.
6. Repeat step 5 until you cannot pick more characters.
7. Repeat the steps from 1 to 6 until you pick all characters from `s`.
In each step, If the smallest or the largest character appears more than once you can choose any occurrence and append it to the result.
Return _the result string after sorting_ `s` _with this algorithm_.
**Example 1:**
**Input:** s = "aaaabbbbcccc"
**Output:** "abccbaabccba"
**Explanation:** After steps 1, 2 and 3 of the first iteration, result = "abc"
After steps 4, 5 and 6 of the first iteration, result = "abccba"
First iteration is done. Now s = "aabbcc" and we go back to step 1
After steps 1, 2 and 3 of the second iteration, result = "abccbaabc"
After steps 4, 5 and 6 of the second iteration, result = "abccbaabccba"
**Example 2:**
**Input:** s = "rat"
**Output:** "art"
**Explanation:** The word "rat" becomes "art" after re-ordering it with the mentioned algorithm.
**Constraints:**
* `1 <= s.length <= 500`
* `s` consists of only lowercase English letters.