A similarity table

Four plants are scored on six characters, coded $1$ (present) or $0$ (absent). You will count the characters alike for a pair, turn it into a per cent, and find the most alike pair.

The idea. Numerical taxonomy gives every character the same weight. Similarity = characters alike ÷ characters scored × 100.

Your tasks.

1. In alike, return the number of positions where the two codes are the same.
2. In similarity, return the per cent, using alike.
3. Set best_pair to the pair of names with the highest similarity.