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Description
tab: English
<p>You are given an <em>absolute</em> path for a Unix-style file system, which always begins with a slash <code>'/'</code>. Your task is to transform this absolute path into its <strong>simplified canonical path</strong>.</p>
<p>The <em>rules</em> of a Unix-style file system are as follows:</p>
<ul>
<li>A single period <code>'.'</code> represents the current directory.</li>
<li>A double period <code>'..'</code> represents the previous/parent directory.</li>
<li>Multiple consecutive slashes such as <code>'//'</code> and <code>'///'</code> are treated as a single slash <code>'/'</code>.</li>
<li>Any sequence of periods that does <strong>not match</strong> the rules above should be treated as a <strong>valid directory or</strong> <strong>file </strong><strong>name</strong>. For example, <code>'...' </code>and <code>'....'</code> are valid directory or file names.</li>
</ul>
<p>The simplified canonical path should follow these <em>rules</em>:</p>
<ul>
<li>The path must start with a single slash <code>'/'</code>.</li>
<li>Directories within the path must be separated by exactly one slash <code>'/'</code>.</li>
<li>The path must not end with a slash <code>'/'</code>, unless it is the root directory.</li>
<li>The path must not have any single or double periods (<code>'.'</code> and <code>'..'</code>) used to denote current or parent directories.</li>
</ul>
<p>Return the <strong>simplified canonical path</strong>.</p>
<p> </p>
<p><strong class="example">Example 1:</strong></p>
<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">path = "/home/"</span></p>
<p><strong>Output:</strong> <span class="example-io">"/home"</span></p>
<p><strong>Explanation:</strong></p>
<p>The trailing slash should be removed.</p>
</div>
<p><strong class="example">Example 2:</strong></p>
<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">path = "/home//foo/"</span></p>
<p><strong>Output:</strong> <span class="example-io">"/home/foo"</span></p>
<p><strong>Explanation:</strong></p>
<p>Multiple consecutive slashes are replaced by a single one.</p>
</div>
<p><strong class="example">Example 3:</strong></p>
<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">path = "/home/user/Documents/../Pictures"</span></p>
<p><strong>Output:</strong> <span class="example-io">"/home/user/Pictures"</span></p>
<p><strong>Explanation:</strong></p>
<p>A double period <code>".."</code> refers to the directory up a level (the parent directory).</p>
</div>
<p><strong class="example">Example 4:</strong></p>
<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">path = "/../"</span></p>
<p><strong>Output:</strong> <span class="example-io">"/"</span></p>
<p><strong>Explanation:</strong></p>
<p>Going one level up from the root directory is not possible.</p>
</div>
<p><strong class="example">Example 5:</strong></p>
<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">path = "/.../a/../b/c/../d/./"</span></p>
<p><strong>Output:</strong> <span class="example-io">"/.../b/d"</span></p>
<p><strong>Explanation:</strong></p>
<p><code>"..."</code> is a valid name for a directory in this problem.</p>
</div>
<p> </p>
<p><strong>Constraints:</strong></p>
<ul>
<li><code>1 <= path.length <= 3000</code></li>
<li><code>path</code> consists of English letters, digits, period <code>'.'</code>, slash <code>'/'</code> or <code>'_'</code>.</li>
<li><code>path</code> is a valid absolute Unix path.</li>
</ul>
---
[submissions](https://leetcode.com/problems/simplify-path/submissions/) | [solutions](https://leetcode.com/problems/simplify-path/solutions/)
tab: 中文
<p>给你一个字符串 <code>path</code> ，表示指向某一文件或目录的 Unix 风格 <strong>绝对路径 </strong>（以 <code>'/'</code> 开头），请你将其转化为 <strong>更加简洁的规范路径</strong>。</p>
<p class="MachineTrans-lang-zh-CN">在 Unix 风格的文件系统中规则如下：</p>
<ul>
<li class="MachineTrans-lang-zh-CN">一个点 <code>'.'</code> 表示当前目录本身。</li>
<li class="MachineTrans-lang-zh-CN">此外，两个点 <code>'..'</code> 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> 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> 或 <code>'....'</code>）均被视为有效的文件/目录名称。</li>
</ul>
<p>返回的 <strong>简化路径</strong> 必须遵循下述格式：</p>
<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）<strong>不能 </strong>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>
<p>返回简化后得到的 <strong>规范路径</strong> 。</p>
<p> </p>
<p><strong class="example">示例 1：</strong></p>
<div class="example-block">
<p><strong>输入：</strong><span class="example-io">path = "/home/"</span></p>
<p><span class="example-io"><b>输出：</b>"/home"</span></p>
<p><strong>解释：</strong></p>
<p>应删除尾随斜杠。</p>
</div>
<p><strong class="example">示例 2：</strong></p>
<div class="example-block">
<p><span class="example-io"><b>输入：</b>path = "/home//foo/"</span></p>
<p><span class="example-io"><b>输出：</b>"/home/foo"</span></p>
<p><strong>解释：</strong></p>
<p>多个连续的斜杠被单个斜杠替换。</p>
</div>
<p><strong class="example">示例 3：</strong></p>
<div class="example-block">
<p><strong>输入：</strong><span class="example-io">path = "/home/user/Documents/../Pictures"</span></p>
<p><span class="example-io"><b>输出：</b>"/home/user/Pictures"</span></p>
<p><strong>解释：</strong></p>
<p>两个点 <code>".."</code> 表示上一级目录（父目录）。</p>
</div>
<p><strong class="example">示例 4：</strong></p>
<div class="example-block">
<p><span class="example-io"><b>输入：</b>path = "/../"</span></p>
<p><span class="example-io"><b>输出：</b>"/"</span></p>
<p><strong>解释：</strong></p>
<p>不可能从根目录上升一级目录。</p>
</div>
<p><strong class="example">示例 5：</strong></p>
<div class="example-block">
<p><span class="example-io"><b>输入：</b>path = "/.../a/../b/c/../d/./"</span></p>
<p><span class="example-io"><b>输出：</b>"/.../b/d"</span></p>
<p><strong>解释：</strong></p>
<p><code>"..."</code> 在这个问题中是一个合法的目录名。</p>
</div>
<p> </p>
<p><strong>提示：</strong></p>
<ul>
<li><code>1 <= path.length <= 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>
---
[提交记录](https://leetcode.cn/problems/simplify-path/submissions/) | [题解](https://leetcode.cn/problems/simplify-path/solution/)
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