:type path: str
    :rtype: str

def simplify_path(path):
    """
    :type path: str
    :rtype: str
    """
    skip = {'..', '.', ''}
    stack = []
    paths = path.split('/')
    for tok in paths:
        if tok == '..':
            if stack:
                stack.pop()
        elif tok not in skip:
            stack.append(tok)
    return '/' + '/'.join(stack)