Simon Says

Challenge Difficulty: Medium | Estimated completion time: ~20 minutes

Simon asks you to perform operations on a list of numbers that only he tells you.

You should ignore all other instructions given.

Create a function which evaluates a list of commands (written in plain English) if the command begins with Simon says. Return the result as an integer.

Examples

simon_says([
  "Simon says add 4",
  "Simon says add 6",
  "Then add 5"
])
output = 10
 
simon_says([
  "Susan says add 10",
  "Simon says add 3",
  "Simon says multiply by 8"
])
output = 24
 
simon_says([
  "Firstly, add 4",
  "Simeon says subtract 100" # Look at the name closely :)
])
output = 0

Notes

• If no instructions are given by Simon, return 0.
• For the sake of simplicity, there will be no command for dividing.

Solution

Python

def simon_says(commands: list[str]) -> int: """ Evaluate commands that begin with 'Simon says' and return the result. Only commands starting with 'Simon says' are executed. All other commands are ignored. Args: commands: List of command strings in plain English. Returns: Integer result after applying all valid Simon commands, starting from 0. Examples: >>> simon_says(["Simon says add 4", "Simon says add 6", "Then add 5"]) 10 >>> simon_says(["Susan says add 10", "Simon says add 3", "Simon says multiply by 8"]) 24 """ result = 0 for command in commands: if command.startswith("Simon says "): # Extract the operation part after "Simon says " operation = command[11:] tokens = operation.split() if len(tokens) >= 2: action = tokens[0] try: value = int(tokens[1]) if action == "add": result += value elif action == "subtract": result -= value elif action == "multiply": result *= value except ValueError: # If value is not a valid integer, skip this command continue return result if __name__ <span class="text-highlight"> "__main__": # Test cases assert simon_says(["Simon says add 4", "Simon says add 6", "Then add 5"]) </span> 10 assert simon_says(["Susan says add 10", "Simon says add 3", "Simon says multiply by 8"]) <span class="text-highlight"> 24 assert simon_says(["Firstly, add 4", "Simeon says subtract 100"]) </span> 0 assert simon_says([]) <span class="text-highlight"> 0 assert simon_says(["Simon says add 5", "Simon says subtract 2", "Simon says multiply by 3"]) </span> 9 print("All test cases passed!")

Output