Attempted: 1

Write a function called `calculate`

which takes an input
string `expression`

and computes the given expression and
returns the values. The expression will only contain the four basic
athematic operations `+`

(addition), `-`

(subtraction), `*`

(multiplication), and `/`

(division). The expression may contain brackets `()`

to check
the order of operations. By default multiplication and division take
higher precedence than addition and subtraction. Unary operations will
not be used (for example `-2`

will not be used, but
`5 - 2`

will be used).

Examples:

```
Input: 5
Output: 5
```

```
Input: 2 + 3 * 4
Output: 14
```

```
Input: (2 + 3) * 4
Output: 20
```

Attempted: 0

Given an array `arr`

of `n`

integers. In each
operation, the system can increase the ith element by 1 (i.e. set
`arr[i] = arr[i] + 1`

, where `1 <= i <= n`

).
The task is to calculate the minimum number of operations required such
that there is no prefix in the array `arr`

whose sum is less
than 0 (i.e. for all `i`

, ```
arr[0] + arr[1] + arr[2] + … +
arr[i] = 0
```

).

Example 1:

```
Input: arr = [2, -3, 1]
Output: 1
Reasoning: The operation can increase the 2nd element of the array by 1.
```

Example 2:

```
Input: arr = [5]
Output: 0
Reasoning: No operations are required.
```

Your task is to write a function called `min_ops`

which
takes in an integer array `arr`

and returns the minimum
number of operations.

Attempted: 2

Write a function called `sum_n_primes`

which takes an
integer `n`

and computes the sum of the first n prime
numbers.

Attempted: 2

The Fibonacci series is given by adding the previous 2 terms of the
series. The first 2 terms of the series are 0 and 1. Your task is to
write a function called `fibonacci`

which takes in a positive
integer `n`

and returns the `nth`

Fibonacci value.
The starting few values in the series is as follows 0, 1, 1, 2, 3, 5, 8,
13, …

Attempted: 3

Write a function which takes in `n`

numbers
(`int`

or `float`

) and returns the sum of the
numbers.