Program to find goal parser interpretation command in Python

Suppose we have a Goal Parser that can interpret a given string command. A command consists of:

• An alphabet "G"

• Opening and closing parenthesis "()"

• and/or "(al)" in some order

Our Goal Parser will interpret "G" as the string "G", "()" as "o", and "(al)" as the string "al". Finally interpreted strings are then concatenated in the original order.

Problem Statement

Given a string command, we need to find the Goal Parser's interpretation of the command.

For example, if the input is command = "G()()()(al)(al)", then the output will be "Goooalal".

Approach

To solve this, we will follow these steps:

• Initialize an empty string to store the result

• Iterate through each character in the command string

• If the character is "G", add it directly to the result

• If we encounter "()", replace it with "o"

• If we encounter "(al)", replace it with "al"

• Return the final interpreted string

Solution Using String Replacement

The simplest approach is to use Python's built-in replace() method ?

def interpret_command(command):
    # Replace patterns in order
    result = command.replace("()", "o")
    result = result.replace("(al)", "al")
    return result

# Test the function
command = "G()()()(al)(al)"
print(f"Input: {command}")
print(f"Output: {interpret_command(command)}")

Input: G()()()(al)(al)
Output: Goooalal

Solution Using Character-by-Character Processing

We can also solve this by iterating through the string character by character ?

def interpret_command_manual(command):
    result = ""
    i = 0
    
    while i < len(command):
        if command[i] == 'G':
            result += 'G'
            i += 1
        elif command[i] == '(' and i + 1 < len(command) and command[i + 1] == ')':
            result += 'o'
            i += 2  # Skip both '(' and ')'
        elif command[i:i+4] == '(al)':
            result += 'al'
            i += 4  # Skip '(al)'
        else:
            i += 1
    
    return result

# Test the function
command = "G()()()(al)(al)"
print(f"Input: {command}")
print(f"Output: {interpret_command_manual(command)}")

Output: Goooalal

Testing with Multiple Examples

Let's test our solution with different command strings ?

def interpret_command(command):
    result = command.replace("()", "o")
    result = result.replace("(al)", "al")
    return result

# Test cases
test_commands = [
    "G()()()(al)(al)",
    "G()",
    "(al)",
    "G()G()()(al)",
    "G(al)"
]

for cmd in test_commands:
    output = interpret_command(cmd)
    print(f"'{cmd}' -> '{output}'")

'G()()()(al)(al)' -> 'Goooalal'
'G()' -> 'Go'
'(al)' -> 'al'
'G()G()()(al)' -> 'GoGoal'
'G(al)' -> 'Gal'

Comparison

Conclusion

The Goal Parser interpretation can be efficiently solved using Python's string replace() method. This approach is clean, readable, and handles all the transformation rules in just two lines of code.