Whats wrong in this code

#1
#2

Hey,you are not taking mod.It might be possible that the count is greater than integer limit.Take mod and try submitting again.

#3

This is how to take mod:

dp[i]=(2*dp[i-1])%mod;
if(previous_count[s[i-1]]!=-1)
dp[i]=(dp[i]-dp[previous_count[s[i-1]]-1]+mod)%mod;

#4

what should be value of mod

#5

It is given in the question. Please check it