Programming Challenge #1488

Implement a "diff" program.
Input: two strings or files that may potentially be quite long.
Output: An edit sequence of inserts and deletes to go from one to the other.

in sudocode:

result = []

for each letter in input1
do
result.add(new replaceop(actiontype.remove, letter))
done

for each letter in input2
do
result.add(new replaceop(actiontype.add, letter))
done

return result