Codility

optimizing_farthest_equal.py

def solution(A):
    highest_distance = 0
    earliest_seen = {}
    for index, value in enumerate(A):
        if earliest_seen.get(value):
            distance = index - earliest_seen[value] + 1
            if distance > highest_distance:
                highest_distance = distance
        else:
            earliest_seen[value] = index + 1
    return highest_distance

word_machine_emulator.py

def solution(S):
    max_integer = 2 ** 20 - 1
    is_valid_int = lambda n: 0 <= n <= max_integer
    ERROR_CODE = -1
    stack = []
    try:
        for token in S.split():
            if token == "POP":
                stack.pop()
            elif token == "DUP":
                temp_token = stack.pop()
                stack.append(temp_token)
                stack.append(temp_token)
            elif token == "+":
                result = stack.pop() + stack.pop()
                if is_valid_int(result):
                    stack.append(result)
                else:
                    return ERROR_CODE
            elif token == "-":
                result = stack.pop() - stack.pop()
                if is_valid_int(result):
                    stack.append(result)
                else:
                    return ERROR_CODE
            else:
                result = int(token)
                if is_valid_int(result):
                    stack.append(result)
                else:
                    return ERROR_CODE
        return stack.pop()
    except IndexError:
        return ERROR_CODE