How can you search for similar sentences in meaning?

Question

Neural networks

We need an algorithm/library to search for sentences similar in meaning in Russian.
Conditionally, in the database there is a question-answer. You need to find the sentence closest in meaning and answer it.
The context does not need to be taken into account, the answers should be fast: 1-3 seconds.
What to use: word2vec, search by keywords somehow?

Answer 1

1. Using word2vec we get vectors for each word
   
2. For each answer, we calculate the vector as the average of the vectors of words from which it consists
   
3. We consider the question vector as the average of the word vectors of which it consists
   
4. For a specific question, we are looking for an answer using, for example, cosine distance