LeetCode [844] Backspace String Compare

 844. Backspace String Compare

Easy

Given two strings S and T, return 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 = "#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".

Note:

• 1 <= S.length <= 200
• 1 <= 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?

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class Solution { public boolean backspaceCompare(String S, String T) { return process(S).equals(process(T)); } String process(String S){ StringBuilder sb = new StringBuilder(); for(char c : S.toCharArray()){ if(c=='#'){ if(sb.length()>0) sb.deleteCharAt(sb.length()-1); }else{ sb.append(c); } } return sb.toString(); } }