These two problems seem to be on every list of programming interview questions:
1) Remove all duplicate characters from a string. Thus, “aaabbb” becomes “ab” and “abcbd” becomes “abcd”.
2) Replace all runs of consecutive spaces with a single space. Thus, “a.b” is unchanged and “a..b” becomes “a.b”, using a dot to make the space visible.
Your task is to write the two requested functions. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.