# 0844. Backspace String Compare

<https://leetcode.com/problems/backspace-string-compare>

## Description

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 = "#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".
```

**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?

## ac

```java
```