Python | Solve given list containing numbers and arithmetic operators

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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