DSUBSEQ - Distinct Subsequences

Given a string, count the number of distinct subsequences of it ( including empty subsequence ). For the uninformed, A subsequence of a string is a new string which is formed from the original string by deleting some of the characters without disturbing the relative positions of the remaining characters.
For example, "AGH" is a subsequence of "ABCDEFGH" while "AHG" is not.


First line of input contains an integer T which is equal to the number of test cases. You are required to process all test cases. Each of next T lines contains a string s.


Output consists of T lines. Ith line in the output corresponds to the number of distinct subsequences of ith input string. Since, this number could be very large, you need to output ans%1000000007 where ans is the number of distinct subsequences.




Constraints and Limits

T ≤ 100, length(S) ≤ 100000
All input strings shall contain only uppercase letters.

hide comments
praval_singhal: 2016-05-17 15:23:51

Misread Max String Length as 10,000. Got SegFault. AC in 2nd Attempt. :)

Megreli: 2016-05-12 12:47:02

I have o(n) solution in Java and getting TLE :\

top34051: 2016-04-19 07:57:18

The best!!

Archit Jain: 2016-04-15 15:39:14

really nice DP

lakshay_v06: 2016-03-24 09:17:58

Woaaahhh! Gr8 Question. Done in O(n) :) .... Thanks to Shashank Tiwari for the tips! :D

Last edit: 2016-03-24 09:19:35
Vikrant Singh: 2016-03-02 10:38:39

beauty !

PRANJIT BHARALI: 2016-02-04 22:22:33

be careful with MOD ...!!!

SM_92: 2015-12-25 13:08:34

Thanks to Shashank Tiwari for his comment , got ac after correcting mod problem.

Utkarsh Agarwal: 2015-12-08 02:07:01

Any python code accepted ?? mine is giving tle . same logic accepted in c++

rahul2907: 2015-09-26 14:05:23

do, if value of sum<0 then sum+=MOD
hope this will helps :)

Added by:Ajay Somani
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: CPP
Resource:CodeCraft 08, Problem Setter: Jin Bin