# 844. Backspace String Compare

Backspace String Compare - LeetCode

Given two strings s and t, return true if they are equal when both are typed into empty text editors. ‘#’ means a backspace character. Note that after backspacing an empty text, the text will continue empty.

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 = “b” Output: false Explanation: s becomes “c” while t becomes “b”.

Constraints:

``````1 <= s.length, t.length <= 200
s and t only contain lowercase letters and '#' characters.
``````

• code
``````class Solution:
def backspaceCompare(self, s: str, t: str) -> bool:
def build(s):
stack = []
for c in s:
if c != "#": stack.append(c)
elif stack: stack.pop()
return "".join(stack)

return build(s) == build(t)
``````
• code
``````class Solution(object):
def backspaceCompare(self, S, T):
def F(S):
skip = 0
for x in reversed(S):
if x == '#':
skip += 1
elif skip:
skip -= 1
else:
yield x

return all(x == y for x, y in itertools.zip_longest(F(S), F(T)))
``````