amazon | Split a String Into the Max Number of Unique Substrings

class Solution:
    def maxUniqueSplit(self, s: str) -> int:
        ans=[0]
        def rec(ind,n,seti):
            if ind==n:
                ans[0]=max(ans[0],len(seti))
                return
            t=""
            for i in range(ind,n):
                t+=s[i]
                if t not in seti:
                    seti.add(t)
                    rec(i+1,n,seti)
                    seti.remove(t)
        seti=set()
        rec(0,len(s),seti)
        return ans[0]