LeetCode in Kotlin
1209. Remove All Adjacent Duplicates in String II
Medium
You are given a string s and an integer k, a k duplicate removal consists of choosing k adjacent and equal letters from s and removing them, causing the left and the right side of the deleted substring to concatenate together.
We repeatedly make k duplicate removals on s until we no longer can.
Return the final string after all such duplicate removals have been made. It is guaranteed that the answer is unique.
Example 1:
Input: s = “abcd”, k = 2
Output: “abcd”
Explanation: There’s nothing to delete.
Example 2:
Input: s = “deeedbbcccbdaa”, k = 3
Output: “aa”
Explanation:
First delete “eee” and “ccc”, get “ddbbbdaa”
Then delete “bbb”, get “dddaa”
Finally delete “ddd”, get “aa”
Example 3:
Input: s = “pbbcggttciiippooaais”, k = 2
Output: “ps”
Constraints:
1 <= s.length <= 1052 <= k <= 104sonly contains lower case English letters.
Solution
class Solution {
fun removeDuplicates(s: String, k: Int): String {
val sb = StringBuilder()
var dupCount = 0
for (i in s.indices) {
if (sb.isNotEmpty() && sb[sb.length - 1] == s[i]) {
dupCount++
} else {
dupCount = 1
}
sb.append(s[i])
if (dupCount == k) {
sb.setLength(sb.length - k)
if (i + 1 < s.length) {
dupCount = 0
for (j in sb.length - 1 downTo 0) {
if (sb[j] == s[i + 1]) {
dupCount++
} else {
break
}
}
}
}
}
return sb.toString()
}
}