#125

[@52nevil36]

thanks bro

[@eklavya22k34]

Thanks for explaining , code is simple, only understanding is the main part. It will be nice if u could explain 2 examples separately by making a full dig. from starting till all subsequences are covered. Once ex. is understood, code is doable if anyone has covered the basic. Thanks again. Tc.

[@PlacementsReady]

Ok thanks for the suggestions

[@abhishekkumar-gi5xm]

it is not necessary to make us understand in english ... hindi me smjhate to aacha rehta.. aur aache se smjh me aata

[@PlacementsReady]

Where u faced the issue ?

[@HarshGuptaNITP]

why you subtracted dp[index-1]? as the answer is stored in in dp[index]as dp[0]=1, dp[1]=2 so you are following one based indexing

[@PlacementsReady]

We need to ignore the subsequence that contains that character that is why index-1

[@sushantsuman4329]

why ggf output is 6 and gfg is 7? both are same

[@PlacementsReady]

Do a dry run according to algo u will understand

[@nithinn2632]

in string "gfg", why "ggf" and "fgg" is not a substring?

[@rainywinter459]

We are finding subsequences not substring

[@PlacementsReady]

Bro by mistake I told substring while explaining

[@PlacementsReady]

Order should be followed that's why ggf and fgg is not a subsequence

[@ScaraB01]

Can u tell in python

[@piyushverma1303]

def distinctSubsequences(self, s): dp=[0]*(len(s)+1) dp[0]=1 mp={} for i in range(1,len(s)+1): dp[i]=2*dp[i-1] if s[i-1] in mp: dp[i]=(dp[i]-dp[mp[s[i-1]]-1])%1000000007 mp[s[i-1]]=i return dp[len(s)]

[@PlacementsReady]

For reference Java and python code is attached in description of video