simplify-path

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Algorithms

You are given an absolute path for a Unix-style file system, which always begins with a slash <code>&#39;/&#39;</code>. Your task is to transform this absolute path into its simplified canonical path.

The rules of a Unix-style file system are as follows:

<ul>
	<li>A single period <code>&#39;.&#39;</code> represents the current directory.</li>
	<li>A double period <code>&#39;..&#39;</code> represents the previous/parent directory.</li>
	<li>Multiple consecutive slashes such as <code>&#39;//&#39;</code> and <code>&#39;///&#39;</code> are treated as a single slash <code>&#39;/&#39;</code>.</li>
	<li>Any sequence of periods that does not match the rules above should be treated as a valid directory or file name. For example, <code>&#39;...&#39; </code>and <code>&#39;....&#39;</code> are valid directory or file names.</li>
</ul>

The simplified canonical path should follow these rules:

<ul>
	<li>The path must start with a single slash <code>&#39;/&#39;</code>.</li>
	<li>Directories within the path must be separated by exactly one slash <code>&#39;/&#39;</code>.</li>
	<li>The path must not end with a slash <code>&#39;/&#39;</code>, unless it is the root directory.</li>
	<li>The path must not have any single or double periods (<code>&#39;.&#39;</code> and <code>&#39;..&#39;</code>) used to denote current or parent directories.</li>
</ul>

Return the simplified canonical path.

&nbsp;
Example 1:

<div class="example-block">
Input: path = &quot;/home/&quot;

Output: &quot;/home&quot;

Explanation:

The trailing slash should be removed.
</div>

Example 2:

<div class="example-block">
Input: path = &quot;/home//foo/&quot;

Output: &quot;/home/foo&quot;

Explanation:

Multiple consecutive slashes are replaced by a single one.
</div>

Example 3:

<div class="example-block">
Input: path = &quot;/home/user/Documents/../Pictures&quot;

Output: &quot;/home/user/Pictures&quot;

Explanation:

A double period <code>&quot;..&quot;</code> refers to the directory up a level (the parent directory).
</div>

Example 4:

<div class="example-block">
Input: path = &quot;/../&quot;

Output: &quot;/&quot;

Explanation:

Going one level up from the root directory is not possible.
</div>

Example 5:

<div class="example-block">
Input: path = &quot;/.../a/../b/c/../d/./&quot;

Output: &quot;/.../b/d&quot;

Explanation:

<code>&quot;...&quot;</code> is a valid name for a directory in this problem.
</div>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= path.length &lt;= 3000</code></li>
	<li><code>path</code> consists of English letters, digits, period <code>&#39;.&#39;</code>, slash <code>&#39;/&#39;</code> or <code>&#39;_&#39;</code>.</li>
	<li><code>path</code> is a valid absolute Unix path.</li>
</ul>

simplifyPath

Simplify Path

Stack

String

给你一个字符串 <code>path</code> ，表示指向某一文件或目录的&nbsp;Unix 风格 绝对路径 （以 <code>'/'</code> 开头），请你将其转化为 更加简洁的规范路径。

在 Unix 风格的文件系统中规则如下：

<ul>
	<li class="MachineTrans-lang-zh-CN">一个点&nbsp;<code>'.'</code>&nbsp;表示当前目录本身。</li>
	<li class="MachineTrans-lang-zh-CN">此外，两个点 <code>'..'</code>&nbsp;表示将目录切换到上一级（指向父目录）。</li>
	<li class="MachineTrans-lang-zh-CN">任意多个连续的斜杠（即，<code>'//'</code>&nbsp;或 <code>'///'</code>）都被视为单个斜杠 <code>'/'</code>。</li>
	<li class="MachineTrans-lang-zh-CN">任何其他格式的点（例如，<code>'...'</code>&nbsp;或 <code>'....'</code>）均被视为有效的文件/目录名称。</li>
</ul>

返回的 简化路径 必须遵循下述格式：

<ul>
	<li>始终以斜杠 <code>'/'</code> 开头。</li>
	<li>两个目录名之间必须只有一个斜杠 <code>'/'</code> 。</li>
	<li>最后一个目录名（如果存在）不能 以 <code>'/'</code> 结尾。</li>
	<li>此外，路径仅包含从根目录到目标文件或目录的路径上的目录（即，不含 <code>'.'</code> 或 <code>'..'</code>）。</li>
</ul>

返回简化后得到的 规范路径 。

&nbsp;

示例 1：

<div class="example-block">
输入：path = "/home/"

输出："/home"

解释：

应删除尾随斜杠。
</div>

示例 2：

<div class="example-block">
输入：path = "/home//foo/"

输出："/home/foo"

解释：

多个连续的斜杠被单个斜杠替换。
</div>

示例 3：

<div class="example-block">
输入：path = "/home/user/Documents/../Pictures"

输出："/home/user/Pictures"

解释：

两个点&nbsp;<code>".."</code>&nbsp;表示上一级目录（父目录）。
</div>

示例 4：

<div class="example-block">
输入：path = "/../"

输出："/"

解释：

不可能从根目录上升一级目录。
</div>

示例 5：

<div class="example-block">
输入：path = "/.../a/../b/c/../d/./"

输出："/.../b/d"

解释：

<code>"..."</code>&nbsp;在这个问题中是一个合法的目录名。
</div>

&nbsp;

提示：

<ul>
	<li><code>1 &lt;= path.length &lt;= 3000</code></li>
	<li><code>path</code> 由英文字母，数字，<code>'.'</code>，<code>'/'</code> 或 <code>'_'</code> 组成。</li>
	<li><code>path</code> 是一个有效的 Unix 风格绝对路径。</li>
</ul>