Given a string?s?consisting only of characters?'a',?'b', and?'c'. You are asked to apply the following algorithm on the string any number of times:

1. Pick a?non-empty?prefix from the string?s?where all the characters in the prefix are equal.

2. Pick a?non-empty?suffix from the string?s?where all the characters in this suffix are equal.

3. The prefix and the suffix should not intersect at any index.

4. The characters from the prefix and suffix must be the same.

5. Delete both the prefix and the suffix.

Return?the?minimum length?of?s?after performing the above operation any number of times (possibly zero times).

?

Example 1:

Input: s = "ca"

Output: 2

Explanation: You can't remove any characters, so the string stays as is.

Example 2:

Input: s = "cabaabac"

Output: 0

Explanation: An optimal sequence of operations is:?

- Take prefix = "c" and suffix = "c" and remove them, s = "abaaba".?

- Take prefix = "a" and suffix = "a" and remove them, s = "baab".?

- Take prefix = "b" and suffix = "b" and remove them, s = "aa".?

- Take prefix = "a" and suffix = "a" and remove them, s = "".

Example 3:

Input: s = "aabccabba"

Output: 3

Explanation: An optimal sequence of operations is:?

- Take prefix = "aa" and suffix = "a" and remove them, s = "bccabb".?

- Take prefix = "b" and suffix = "bb" and remove them, s = "cca".

?寫了3個函數(shù)，

1：判斷左右兩端是否一樣，用來做循環(huán)的條件；

2：判斷左邊一樣的到哪里；

3：判斷右邊一樣的到哪里；

依次循環(huán)，處理返回即可；

但是長度為1的需要特殊處理一下即可；

只是沒想到還能速度這么快。。。。

下面是代碼：

Constraints:

• 1 <= s.length <= 105

• s?only consists of characters?'a',?'b', and?'c'.

Runtime:?5 ms, faster than?88.12%?of?Java?online submissions for?Minimum Length of String After Deleting Similar Ends.

Memory Usage:?43.1 MB, less than?60.54%?of?Java?online submissions for?Minimum Length of String After Deleting Similar Ends.