M1461. Check If a String Contains All Binary Codes of Size K

class Solution:
    def hasAllCodes(self, s: str, k: int) -> bool:
        max_num = 2**k-1
        
        while max_num!=-1:
            ss = str(bin(max_num))[2:]
            if len(ss)!=k:
                pp="0"*(k-len(ss))+ss
            else:
                pp=ss
            max_num-=1
            if pp not in s:
                return False
        return True