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Python | Solve given list containing numbers and arithmetic operators
• Last Updated : 29 Mar, 2019

Given a list containing numbers and arithmetic operators, the task is to solve the list.

Example:

```Input: lst =  [2, '+', 22, '+', 55, '+', 4]
Output: 83

Input: lst =  [12, '+', 8, '-', 5]
Output: 15
```

Below are some ways to achieve the above tasks.

Method #1: Using Iteration
We can use iteration as the simplest approach to solve the list with importing different operators.

 `# Python code to solve the list``# containing numbers and arithmetic operators`` ` `# Importing``from` `operator ``import` `add, sub`` ` `# Function to solve list``def` `find(``Input``):``    ``ans ``=` `0``    ``options ``=` `{``'+'``: add, ``'-'``: sub}``    ``option ``=` `add ``    ``for` `item ``in` `Input``:``        ``if` `item ``in` `options:``            ``option ``=` `options[item]``        ``else``:``            ``number ``=` `float``(item)``            ``ans ``=` `option(ans, number)``    ``return` `ans`` ` `# Input Initialization``lst ``=` `[``91``, ``'+'``, ``132``, ``'-'``, ``156``, ``'+'``, ``4``]`` ` `# Calling function``Output ``=` `find(lst)`` ` `# Printing output``print``(``"Initial list"``, lst)``print``(``"Answer after solving list is:"``, Output)`
Output:

```Initial list [91, '+', 132, '-', 156, '+', 4]
Answer after solving list is: 71.0
```

Method #2: Using eval and join

 `# Python code to solve the list``# containing numbers and arithmetic operators`` ` `# Input list initialization``lst ``=`  `[``2``, ``'+'``, ``22``, ``'+'``, ``55``, ``'+'``, ``4``]`` ` `# Using eval and join``Output ``=` `eval``(``' '``.join(``str``(x) ``for` `x ``in` `lst))`` ` `# Printing output``print``(``"Initial list"``, lst)``print``(``"Answer after solving list is:"``, Output)`
Output:
```Initial list [2, '+', 22, '+', 55, '+', 4]
Answer after solving list is: 83
```

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