final-value-of-variable-after-performing-operations

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Algorithms

There is a programming language with only four operations and one variable <code>X</code>:

<ul>
	<li><code>++X</code> and <code>X++</code> increments the value of the variable <code>X</code> by <code>1</code>.</li>
	<li><code>--X</code> and <code>X--</code> decrements the value of the variable <code>X</code> by <code>1</code>.</li>
</ul>

Initially, the value of <code>X</code> is <code>0</code>.

Given an array of strings <code>operations</code> containing a list of operations, return the final value of <code>X</code> after performing all the operations.

&nbsp;
Example 1:

<pre>
Input: operations = [&quot;--X&quot;,&quot;X++&quot;,&quot;X++&quot;]
Output: 1
Explanation:&nbsp;The operations are performed as follows:
Initially, X = 0.
--X: X is decremented by 1, X = 0 - 1 = -1.
X++: X is incremented by 1, X = -1 + 1 = 0.
X++: X is incremented by 1, X = 0 + 1 = 1.
</pre>

Example 2:

<pre>
Input: operations = [&quot;++X&quot;,&quot;++X&quot;,&quot;X++&quot;]
Output: 3
Explanation: The operations are performed as follows:
Initially, X = 0.
++X: X is incremented by 1, X = 0 + 1 = 1.
++X: X is incremented by 1, X = 1 + 1 = 2.
X++: X is incremented by 1, X = 2 + 1 = 3.
</pre>

Example 3:

<pre>
Input: operations = [&quot;X++&quot;,&quot;++X&quot;,&quot;--X&quot;,&quot;X--&quot;]
Output: 0
Explanation:&nbsp;The operations are performed as follows:
Initially, X = 0.
X++: X is incremented by 1, X = 0 + 1 = 1.
++X: X is incremented by 1, X = 1 + 1 = 2.
--X: X is decremented by 1, X = 2 - 1 = 1.
X--: X is decremented by 1, X = 1 - 1 = 0.
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= operations.length &lt;= 100</code></li>
	<li><code>operations[i]</code> will be either <code>&quot;++X&quot;</code>, <code>&quot;X++&quot;</code>, <code>&quot;--X&quot;</code>, or <code>&quot;X--&quot;</code>.</li>
</ul>

finalValueAfterOperations

Final Value of Variable After Performing Operations

Array

String

Simulation

存在一种仅支持 4 种操作和 1 个变量 <code>X</code> 的编程语言：

<ul>
	<li><code>++X</code> 和 <code>X++</code> 使变量 <code>X</code> 的值 加 <code>1</code></li>
	<li><code>--X</code> 和 <code>X--</code> 使变量 <code>X</code> 的值 减 <code>1</code></li>
</ul>

最初，<code>X</code> 的值是 <code>0</code>

给你一个字符串数组 <code>operations</code> ，这是由操作组成的一个列表，返回执行所有操作后， <code>X</code> 的 最终值 。

&nbsp;

示例 1：

<pre>
输入：operations = ["--X","X++","X++"]
输出：1
解释：操作按下述步骤执行：
最初，X = 0
--X：X 减 1 ，X = 0 - 1 = -1
X++：X 加 1 ，X = -1 + 1 = 0
X++：X 加 1 ，X = 0 + 1 = 1
</pre>

示例 2：

<pre>
输入：operations = ["++X","++X","X++"]
输出：3
解释：操作按下述步骤执行： 
最初，X = 0
++X：X 加 1 ，X = 0 + 1 = 1
++X：X 加 1 ，X = 1 + 1 = 2
X++：X 加 1 ，X = 2 + 1 = 3
</pre>

示例 3：

<pre>
输入：operations = ["X++","++X","--X","X--"]
输出：0
解释：操作按下述步骤执行：
最初，X = 0
X++：X 加 1 ，X = 0 + 1 = 1
++X：X 加 1 ，X = 1 + 1 = 2
--X：X 减 1 ，X = 2 - 1 = 1
X--：X 减 1 ，X = 1 - 1 = 0
</pre>

&nbsp;

提示：

<ul>
	<li><code>1 &lt;= operations.length &lt;= 100</code></li>
	<li><code>operations[i]</code> 将会是 <code>"++X"</code>、<code>"X++"</code>、<code>"--X"</code> 或 <code>"X--"</code></li>
</ul>