public class RemoveAllAdjacentDuplicatesInString {

    /*

    解法一：栈

     */

    public String removeDuplicates(String S) {

        Stack<Character> stack=new Stack<>();

        for (char c:S.toCharArray()){

            if (stack.isEmpty()||c!=stack.peek())

                stack.push(c);

            else

                stack.pop();

        }

        StringBuilder stringBuilder=new StringBuilder();

        for (Character character:stack)

            stringBuilder.append(character);

        return stringBuilder.toString();

    }

    /*

    解法二：StringBuilder模拟栈。

     */

    public String removeDuplicates2(String S) {

     StringBuilder stringBuilder=new StringBuilder();

     int length=0;

     for (char c:S.toCharArray()){

        if (length!=0&&c==stringBuilder.charAt(length-1))

            stringBuilder.deleteCharAt(length-- -1);

        else {

            stringBuilder.append(c);

            length++;

        }

     }

     return stringBuilder.toString();

    }

}