Given a string?s?of lower and upper case English letters.

A good string is a string which doesn't have?two adjacent characters?s[i]?and?s[i + 1]?where:

• 0 <= i <= s.length - 2

• s[i]?is a lower-case letter and?s[i + 1]?is the same letter but in upper-case or?vice-versa.

To make the string good, you can choose?two adjacent?characters that make the string bad and remove them. You can keep doing this until the string becomes good.

Return?the string?after making it good. The answer is guaranteed to be unique under the given constraints.

Notice?that an empty string is also good.

?

Example 1:

Input: s = "leEeetcode"Output: "leetcode"Explanation: In the first step, either you choose i = 1 or i = 2, both will result "leEeetcode" to be reduced to "leetcode".

Example 2:

Input: s = "abBAcC"Output: ""Explanation: We have many possible scenarios, and all lead to the same answer. For example: "abBAcC" --> "aAcC" --> "cC" --> "" "abBAcC" --> "abBA" --> "aA" --> ""

Example 3:

Input: s = "s"Output: "s"

這種情況下用ArrayList 最方便了，當刪除后，能自動補全，所以list.remove(i)要寫2次，

類似于數(shù)組的刪除第i項和刪除第i+1項，但是ArrayList 就只能寫2個remove(i)了；

至少咱通過了，不要求別的了。

Runtime:?7 ms, faster than?31.75%?of?Java?online submissions for?Make The String Great.

Memory Usage:?43.8 MB, less than?12.54%?of?Java?online submissions for?Make The String Great.