Day 9: Backspace String Compare.py

# Day 9: Backspace String Compare
# 
# 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 "".
# 
# Note:
# 1 <= S.length <= 200
# 1 <= T.length <= 200
# S and T only contain lowercase letters and '#' characters.


#class Solution(object):
def backspaceCompare(S, T):
    """
    :type S: str
    :type T: str
    :rtype: bool
    """

    new_s = []
    for char in S:
        if (char == "#" and new_s):
            new_s.pop()
        elif char != "#":
            new_s.append(char)

    new_t = []
    for char in T:
        if (char == "#" and new_t): 
            new_t.pop()
        elif char != "#":
            new_t.append(char)
    return new_s == new_t

    
print(backspaceCompare("a##bc", "a##cb")) # False
print(backspaceCompare("ab##", "c#d#"))  # True => both strings become ""
print(backspaceCompare("a#c", "b")) # False