algoadvance

You are given a list of strings operations where each string represents a single operation on a variable X that starts at 0. Only two types of operations are allowed: increment ("++X" or "X++"), and decrement ("--X" or "X--").

Your task is to determine the final value of X after performing all the operations.

Example:

operations = ["--X", "X++", "X++"]

The final value of X should be 1.

Clarifying Questions

  1. Are there any invalid operations in the list?
    • No, all operations in the list are valid (either increment or decrement).
  2. Does the starting value of X always equal 0?
    • Yes, X always starts at 0.
  3. Is the length of the list limited?
    • The list can be of any length, but we assume it fits within the standard constraints of competitive programming exercises.

Strategy

  1. Initialization: Start with X initialized to 0.
  2. Iteration: Iterate through the list of operations.
  3. Condition Checking: Check each operation:
    • If it is an increment operation ("++X" or "X++"), increase X by 1.
    • If it is a decrement operation ("--X" or "X--"), decrease X by 1.
  4. Final Result: Return the final value of X.

Code

Here’s how you can implement this strategy in Python:

def final_value_after_operations(operations):
    X = 0
    for operation in operations:
        if operation in ("++X", "X++"):
            X += 1
        elif operation in ("--X", "X--"):
            X -= 1
    return X

# Example usage
operations = ["--X", "X++", "X++"]
print(final_value_after_operations(operations))  # Output: 1

Time Complexity

The time complexity for this solution is O(n), where n is the number of operations in the list. This is because we are simply iterating through the list once and performing constant-time operations within the loop.

Space Complexity

The space complexity for this solution is O(1). We are only using a fixed amount of extra space for the variable X, regardless of the input size.

Try our interview co-pilot at AlgoAdvance.com