minimum-number-of-chairs-in-a-waiting-room

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Algorithms

You are given a string <code>s</code>. Simulate events at each second <code>i</code>:

<ul>
	<li>If <code>s[i] == &#39;E&#39;</code>, a person enters the waiting room and takes one of the chairs in it.</li>
	<li>If <code>s[i] == &#39;L&#39;</code>, a person leaves the waiting room, freeing up a chair.</li>
</ul>

Return the minimum number of chairs needed so that a chair is available for every person who enters the waiting room given that it is initially empty.

&nbsp;
Example 1:

<div class="example-block">
Input: s = &quot;EEEEEEE&quot;

Output: 7

Explanation:

After each second, a person enters the waiting room and no person leaves it. Therefore, a minimum of 7 chairs is needed.
</div>

Example 2:

<div class="example-block">
Input: s = &quot;ELELEEL&quot;

Output: 2

Explanation:

Let&#39;s consider that there are 2 chairs in the waiting room. The table below shows the state of the waiting room at each second.
</div>

<table>
	<tbody>
		<tr>
			<th>Second</th>
			<th>Event</th>
			<th>People in the Waiting Room</th>
			<th>Available Chairs</th>
		</tr>
		<tr>
			<td>0</td>
			<td>Enter</td>
			<td>1</td>
			<td>1</td>
		</tr>
		<tr>
			<td>1</td>
			<td>Leave</td>
			<td>0</td>
			<td>2</td>
		</tr>
		<tr>
			<td>2</td>
			<td>Enter</td>
			<td>1</td>
			<td>1</td>
		</tr>
		<tr>
			<td>3</td>
			<td>Leave</td>
			<td>0</td>
			<td>2</td>
		</tr>
		<tr>
			<td>4</td>
			<td>Enter</td>
			<td>1</td>
			<td>1</td>
		</tr>
		<tr>
			<td>5</td>
			<td>Enter</td>
			<td>2</td>
			<td>0</td>
		</tr>
		<tr>
			<td>6</td>
			<td>Leave</td>
			<td>1</td>
			<td>1</td>
		</tr>
	</tbody>
</table>

Example 3:

<div class="example-block">
Input: s = &quot;ELEELEELLL&quot;

Output: 3

Explanation:

Let&#39;s consider that there are 3 chairs in the waiting room. The table below shows the state of the waiting room at each second.
</div>

<table>
	<tbody>
		<tr>
			<th>Second</th>
			<th>Event</th>
			<th>People in the Waiting Room</th>
			<th>Available Chairs</th>
		</tr>
		<tr>
			<td>0</td>
			<td>Enter</td>
			<td>1</td>
			<td>2</td>
		</tr>
		<tr>
			<td>1</td>
			<td>Leave</td>
			<td>0</td>
			<td>3</td>
		</tr>
		<tr>
			<td>2</td>
			<td>Enter</td>
			<td>1</td>
			<td>2</td>
		</tr>
		<tr>
			<td>3</td>
			<td>Enter</td>
			<td>2</td>
			<td>1</td>
		</tr>
		<tr>
			<td>4</td>
			<td>Leave</td>
			<td>1</td>
			<td>2</td>
		</tr>
		<tr>
			<td>5</td>
			<td>Enter</td>
			<td>2</td>
			<td>1</td>
		</tr>
		<tr>
			<td>6</td>
			<td>Enter</td>
			<td>3</td>
			<td>0</td>
		</tr>
		<tr>
			<td>7</td>
			<td>Leave</td>
			<td>2</td>
			<td>1</td>
		</tr>
		<tr>
			<td>8</td>
			<td>Leave</td>
			<td>1</td>
			<td>2</td>
		</tr>
		<tr>
			<td>9</td>
			<td>Leave</td>
			<td>0</td>
			<td>3</td>
		</tr>
	</tbody>
</table>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= s.length &lt;= 50</code></li>
	<li><code>s</code> consists only of the letters <code>&#39;E&#39;</code> and <code>&#39;L&#39;</code>.</li>
	<li><code>s</code> represents a valid sequence of entries and exits.</li>
</ul>

minimumChairs

Minimum Number of Chairs in a Waiting Room

Consecutive Characters

consecutive-characters

连续字符

String

Simulation

给你一个字符串 <code>s</code>，模拟每秒钟的事件 <code>i</code>：

<ul>
	<li>如果 <code>s[i] == 'E'</code>，表示有一位顾客进入候诊室并占用一把椅子。</li>
	<li>如果 <code>s[i] == 'L'</code>，表示有一位顾客离开候诊室，从而释放一把椅子。</li>
</ul>

返回保证每位进入候诊室的顾客都能有椅子坐的 最少 椅子数，假设候诊室最初是 空的 。

&nbsp;

示例 1：

<div class="example-block">
输入：s = "EEEEEEE"

输出：7

解释：

每秒后都有一个顾客进入候诊室，没有人离开。因此，至少需要 7 把椅子。
</div>

示例 2：

<div class="example-block">
输入：s = "ELELEEL"

输出：2

解释：

假设候诊室里有 2 把椅子。下表显示了每秒钟等候室的状态。
</div>
<table>
	<tbody>
		<tr>
			<th>秒</th>
			<th>事件</th>
			<th>候诊室的人数</th>
			<th>可用的椅子数</th>
		</tr>
		<tr>
			<td>0</td>
			<td>Enter</td>
			<td>1</td>
			<td>1</td>
		</tr>
		<tr>
			<td>1</td>
			<td>Leave</td>
			<td>0</td>
			<td>2</td>
		</tr>
		<tr>
			<td>2</td>
			<td>Enter</td>
			<td>1</td>
			<td>1</td>
		</tr>
		<tr>
			<td>3</td>
			<td>Leave</td>
			<td>0</td>
			<td>2</td>
		</tr>
		<tr>
			<td>4</td>
			<td>Enter</td>
			<td>1</td>
			<td>1</td>
		</tr>
		<tr>
			<td>5</td>
			<td>Enter</td>
			<td>2</td>
			<td>0</td>
		</tr>
		<tr>
			<td>6</td>
			<td>Leave</td>
			<td>1</td>
			<td>1</td>
		</tr>
	</tbody>
</table>


示例 3：

<div class="example-block">
输入：s = "ELEELEELLL"

输出：3

解释：

假设候诊室里有 3 把椅子。下表显示了每秒钟等候室的状态。
</div>
<table>
	<tbody>
		<tr>
			<th>秒</th>
			<th>事件</th>
			<th>候诊室的人数</th>
			<th>可用的椅子数</th>
		</tr>
		<tr>
			<td>0</td>
			<td>Enter</td>
			<td>1</td>
			<td>2</td>
		</tr>
		<tr>
			<td>1</td>
			<td>Leave</td>
			<td>0</td>
			<td>3</td>
		</tr>
		<tr>
			<td>2</td>
			<td>Enter</td>
			<td>1</td>
			<td>2</td>
		</tr>
		<tr>
			<td>3</td>
			<td>Enter</td>
			<td>2</td>
			<td>1</td>
		</tr>
		<tr>
			<td>4</td>
			<td>Leave</td>
			<td>1</td>
			<td>2</td>
		</tr>
		<tr>
			<td>5</td>
			<td>Enter</td>
			<td>2</td>
			<td>1</td>
		</tr>
		<tr>
			<td>6</td>
			<td>Enter</td>
			<td>3</td>
			<td>0</td>
		</tr>
		<tr>
			<td>7</td>
			<td>Leave</td>
			<td>2</td>
			<td>1</td>
		</tr>
		<tr>
			<td>8</td>
			<td>Leave</td>
			<td>1</td>
			<td>2</td>
		</tr>
		<tr>
			<td>9</td>
			<td>Leave</td>
			<td>0</td>
			<td>3</td>
		</tr>
	</tbody>
</table>


&nbsp;

提示：

<ul>
	<li><code>1 &lt;= s.length &lt;= 50</code></li>
	<li><code>s</code> 仅由字母 <code>'E'</code> 和 <code>'L'</code> 组成。</li>
	<li><code>s</code> 表示一个有效的进出序列。</li>
</ul>

秒	事件	候诊室的人数	可用的椅子数
0	Enter	1	2
1	Leave	0	3
2	Enter	1	2
3	Enter	2	1
4	Leave	1	2
5	Enter	2	1
6	Enter	3	0
7	Leave	2	1
8	Leave	1	2
9	Leave	0	3