  A finite word $f$ is Hamming-isometric if for any two word $u$ and $v$ of
same length avoiding $f$, $u$ can be transformed into $v$ by changing one by
one all the letters on which $u$ differs from $v$, in such a way that all of
the new words obtained in this process also avoid~$f$. Words which are not
Hamming-isometric have been characterized as words having a border with two
mismatches. We derive from this characterization a linear-time algorithm to
check whether a word is Hamming-isometric. It is based on pattern matching
algorithms with $k$ mismatches. Lee-isometric words over a four-letter alphabet
have been characterized as words having a border with two Lee-errors. We derive
from this characterization a linear-time algorithm to check whether a word over
an alphabet of size four is Lee-isometric.
