path-crossing

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Algorithms

Given a string <code>path</code>, where <code>path[i] = &#39;N&#39;</code>, <code>&#39;S&#39;</code>, <code>&#39;E&#39;</code> or <code>&#39;W&#39;</code>, each representing moving one unit north, south, east, or west, respectively. You start at the origin <code>(0, 0)</code> on a 2D plane and walk on the path specified by <code>path</code>.

Return <code>true</code> if the path crosses itself at any point, that is, if at any time you are on a location you have previously visited. Return <code>false</code> otherwise.

&nbsp;
Example 1:
<img alt="" src="https://assets.leetcode.com/uploads/2020/06/10/screen-shot-2020-06-10-at-123929-pm.png" style="width: 400px; height: 358px;" />
<pre>
Input: path = &quot;NES&quot;
Output: false 
Explanation: Notice that the path doesn&#39;t cross any point more than once.
</pre>

Example 2:
<img alt="" src="https://assets.leetcode.com/uploads/2020/06/10/screen-shot-2020-06-10-at-123843-pm.png" style="width: 400px; height: 339px;" />
<pre>
Input: path = &quot;NESWW&quot;
Output: true
Explanation: Notice that the path visits the origin twice.</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= path.length &lt;= 104</code></li>
	<li><code>path[i]</code> is either <code>&#39;N&#39;</code>, <code>&#39;S&#39;</code>, <code>&#39;E&#39;</code>, or <code>&#39;W&#39;</code>.</li>
</ul>

isPathCrossing

Path Crossing

Hash Table

String

给你一个字符串 <code>path</code>，其中 <code>path[i]</code> 的值可以是 <code>'N'</code>、<code>'S'</code>、<code>'E'</code> 或者 <code>'W'</code>，分别表示向北、向南、向东、向西移动一个单位。

你从二维平面上的原点 <code>(0, 0)</code> 处开始出发，按 <code>path</code> 所指示的路径行走。

如果路径在任何位置上与自身相交，也就是走到之前已经走过的位置，请返回 <code>true</code> ；否则，返回 <code>false</code> 。

&nbsp;

示例 1：

<img alt="" src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2020/06/28/screen-shot-2020-06-10-at-123929-pm.png" style="height: 358px; width: 400px;" />

<pre>
输入：path = "NES"
输出：false 
解释：该路径没有在任何位置相交。</pre>

示例 2：

<img alt="" src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2020/06/28/screen-shot-2020-06-10-at-123843-pm.png" style="height: 339px; width: 400px;" />

<pre>
输入：path = "NESWW"
输出：true
解释：该路径经过原点两次。</pre>

&nbsp;

提示：

<ul>
	<li><code>1 &lt;= path.length &lt;= 104</code></li>
	<li><code>path[i]</code> 为 <code>'N'</code>、<code>'S'</code>、<code>'E'</code> 或 <code>'W'</code></li>
</ul>