Implement a string compressor

Write a function that takes a string and returns a compressed version, where consecutive duplicate characters are replaced with a single character followed by the number of repetitions.

For example, “aabccc” becomes “a2bc3”.

1. Fill in the code.
2. You can copy the code into IntelliJ/Android Studio, but it shouldn’t be necessary.
3. Click “run” – the green triangle. The code will compile and several tests will be run.
4. In the logs, you will see “try again” if the solution is incorrect, or “success” and a special code.
5. Provide this code in the form below along with your email and click “send”.
6. Solutions will be presented the next day on Instagram

    fun test1() = compressString("aabccc") == "a2bc3"
    fun test2() = compressString("abcd") == "abcd"
    fun test3() = compressString("aaabaaa") == "a3ba3"
    fun test4() = compressString("") == ""
    fun test5() = compressString("bbbbb") == "b5"