"""

 Given two strings S and T, return if they are equal when both are typed into empty text editors. # means a backspace character.

 Example 1:

 Input: S = "ab#c", T = "ad#c"

 Output: true

 Explanation: Both S and T become "ac".

 Example 2:

 Input: S = "ab##", T = "c#d#"

 Output: true

 Explanation: Both S and T become "".

 Example 3:

 Input: S = "a##c", T = "#a#c"

 Output: true

 Explanation: Both S and T become "c".

 Example 4:

 Input: S = "a#c", T = "b"

 Output: false

 Explanation: S becomes "c" while T becomes "b".

 """

 """

 简单题通过

 """

 class Solution:

     def backspaceCompare(self, S, T):

         """

         :type S: str

         :type T: str

         :rtype: bool

         """

         return self._back(S) == self._back(T)

     def _back(self, string):

         stack = []

         for i in range(len(string)):

             if string[i] == '#':

                 if stack: #这里重要，需要判断stack不为空，对于这种[#a#c]输入

                     stack.pop()

                 continue

             stack.append(string[i])

         return stack