Decodes a single string to a list of strings.
    :type s: str
    :rtype: List[str]

def decode(s):
    """Decodes a single string to a list of strings.
    :type s: str
    :rtype: List[str]
    """
    strs = []
    i = 0
    while i < len(s):
        index = s.find(":", i)
        size = int(s[i:index])
        strs.append(s[index+1: index+1+size])
        i = index+1+size
    return strs