844. Backspace String Compare

📋 Đề Bài

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?

🧠 Thuật Toán & Kỹ Thuật

String (Chuỗi)

⏱️ Thời gian O(n)

💾 Không gian O(1)

💻 Lời Giải

C++ 0844-backspace-string-compare.cpp

class Solution {
public:
    string handleBackspace(string s) {
        string ans;
        for (char c : s) {
            if (c == '#') {
                if (!ans.empty()) {
                    ans.pop_back();
                }
            }
            else {
                ans.push_back(c);
            }
        }
        return ans;
    }
    bool backspaceCompare(string s, string t) {
        return handleBackspace(s) == handleBackspace(t);
    }
};