---
# System prepended metadata

title: 2011. Final Value of Variable After Performing Operations

---

# 2011. Final Value of Variable After Performing Operations

[JavaScript] LeetCode 2011

## 題目概要
- 給定一個陣列 operations，裡面包含著所有操作，x++ 或者 ++x 都代表將 x + 1; 反之 x-- 或 --x 都代表 x - 1，求經過計算後的結果為何。

```
Example 1:

Input: operations = ["--X","X++","X++"]
Output: 1
Explanation: 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.

Example 2:

Input: operations = ["++X","++X","X++"]
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.

Example 3:

Input: operations = ["X++","++X","--X","X--"]
Output: 0
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 decremented by 1, X = 2 - 1 = 1.
X--: X is decremented by 1, X = 1 - 1 = 0.
```

## 解題技巧
- 直接判斷元素包含的是 + 還是 - ，然後將總和進行對應的運算即可。

## 程式碼

```js
var finalValueAfterOperations = function(operations) {
   let sum = 0;
    for(const ele of operations){
        if(ele.includes("+")) sum++
        else sum--
    }
    return sum;
};
```

![](https://i.imgur.com/jxBSIHq.png)
