You are given a string?s?consisting of lowercase English 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 can be proven that the answer is?unique.

?

Example 1:

Input: s = "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".

Example 2:

Input: s = "azxxzy"

Output: "ay"

?

Constraints:

• 1 <= s.length <= 105

• s?consists of lowercase English letters.

看了題目，就覺(jué)得應(yīng)該用stack，但是沒(méi)有沒(méi)有用過(guò)了，只能用stringbuilder，

每次判斷stringbuilder的元素跟目前的元素是否一樣，一樣的話(huà)，就可以刪除sb的最后一個(gè)元素，如果不一樣，添加上該元素就行。

我一直想著數(shù)組，list ，好像都不行的，結(jié)果stringbuilder可以。。。。

Runtime:?13 ms, faster than?87.06%?of?Java?online submissions for?Remove All Adjacent Duplicates In String.

Memory Usage:?42.8 MB, less than?79.21%?of?Java?online submissions for?Remove All Adjacent Duplicates In String.