LeetCode-in-Java
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
public class Solution {
public String removeDuplicates(String s, int k) {
StringBuilder sb = new StringBuilder();
int dupCount = 0;
for (int i = 0; i < s.length(); i++) {
if (sb.length() != 0 && sb.charAt(sb.length() - 1) == s.charAt(i)) {
dupCount++;
} else {
dupCount = 1;
}
sb.append(s.charAt(i));
if (dupCount == k) {
sb.setLength(sb.length() - k);
if (i + 1 < s.length()) {
dupCount = 0;
for (int j = sb.length() - 1; j >= 0; j--) {
if (sb.charAt(j) == s.charAt(i + 1)) {
dupCount++;
} else {
break;
}
}
}
}
}
return sb.toString();
}
}