Backspace String Compare

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.

Follow up: Can you solve it in O(n) time and O(1) space?

SOLUTION:

class Solution:
    def backspaceCompare(self, s: str, t: str) -> bool:
        ss = ""
        tt = ""
        for c in s:
            if c == "#":
                ss = ss[:-1]
            else:
                ss += c
        for c in t:
            if c == "#":
                tt = tt[:-1]
            else:
                tt += c
        return ss == tt