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RemoveAllAdjacentDuplicatesInString.java
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RemoveAllAdjacentDuplicatesInString.java
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package Leetcode;
import java.util.ArrayDeque;
import java.util.Deque;
/**
* @author kalpak
*
* Given a string S of lowercase letters, a duplicate removal consists of choosing two adjacent and equal letters, and removing them.
*
* We repeatedly make duplicate removals on S until we no longer can.
*
* Return the final string after all such duplicate removals have been made. It is guaranteed the answer is unique.
*
*
* Example 1:
* Input: "abbaca"
* Output: "ca"
* Explanation:
* For example, in "abbaca" we could remove "bb" since the letters are adjacent and equal, and this is the only possible move.
* The result of this move is that the string is "aaca", of which only "aa" is possible, so the final string is "ca".
*
*
* Note:
*
* 1 <= S.length <= 20000
* S consists only of English lowercase letters.
*/
public class RemoveAllAdjacentDuplicatesInString {
public static String removeDuplicates(String S) {
Deque<Character> stack = new ArrayDeque<>();
StringBuilder result = new StringBuilder();
for(int i = 0; i < S.length(); i++) {
char c = S.charAt(i);
if(!stack.isEmpty() && stack.peek() == c)
stack.pop();
else
stack.push(c);
}
while(!stack.isEmpty()){
result.insert(0, stack.pop());
}
return result.toString();
}
public static void main(String[] args) {
String str = "abbaca";
System.out.println(removeDuplicates(str));
}
}