Why it is giving wrong ans
@harry_potter123 There are two problem in the code, first you are not taking mod after every operation,
like
sum=((sum%m)*((1+a[i])%m )%m // correct statement
Like this you need to take mod every where
Second you cannot divide by two when we are taking mod division is not allowed, calculate the inverse of 2 under mod, and multiply it with the p you are calculating instead of dividing it. Similary you cannot divide sum by a[i]+1 , instead calculate its inverse modulo.
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