I found this problem in here
(Problem 6 on page 6)
Consider the triple repeat code. What codewords are closest to $(1, 1, 0)$? Describe the set of vectors at distance $1$ or less from the codeword $(0, 0, 0)$. Do the same for the set of vectors at distance $1$ or less from the codeword $(1, 1, 1)$. What is the relation between these two sets? (We think of them as balls of radius one around the respective codewords.) What is the distance between the codewords $(0,0, 0)$ and $(1, 1, 1)$?