Здравейте,

Имам проблем със задача Wourld Tour от финалния изпит. Моля за малко съдействие.

https://pastebin.com/ikUg3XgU

Problem 1 - World Tour
Problem for exam preparation for the Programming Fundamentals Course @SoftUni.
Submit your solutions in the SoftUni judge system at https://judge.softuni.org/Contests/Practice/Index/2518#0.

You are a world traveler, and your next goal is to make a world tour. To do that, you have to plan out everything first. To start with, you would like to plan out all of your stops where you will have a break.
On the first line, you will be given a string containing all of your stops. Until you receive the command "Travel", you will be given some commands to manipulate that initial string. The commands can be:
•    "Add Stop:{index}:{string}":
o    Insert the given string at that index only if the index is valid
•    "Remove Stop:{start_index}:{end_index}":
o    Remove the elements of the string from the starting index to the end index (inclusive) if both indices are valid
•    "Switch:{old_string}:{new_string}":
o    If the old string is in the initial string, replace it with the new one (all occurrences)
Note: After each command, print the current state of the string
After the "Travel" command, print the following: "Ready for world tour! Planned stops: {string}"
Input / Constraints
•    JavaScript: you will receive a list of strings
•    An index is valid if it is between the first and the last element index (inclusive) in the sequence.
Output
•    Print the proper output messages in the proper cases as described in the problem description
Examples
Input    Output
Hawai::Cyprys-Greece
Add Stop:7:Rome
Remove Stop:11:16
Switch:Hawai:Bulgaria
Travel    Hawai::RomeCyprys-Greece
Hawai::Rome-Greece
Bulgaria::Rome-Greece
Ready for world tour! Planned stops: Bulgaria::Rome-Greece
JS Examples
Input    Output
(["Hawai::Cyprys-Greece",
"Add Stop:7:Rome",
"Remove Stop:11:16",
"Switch:Hawai:Bulgaria",
"Travel"])    Hawai::RomeCyprys-Greece
Hawai::Rome-Greece
Bulgaria::Rome-Greece
Ready for world tour! Planned stops: Bulgaria::Rome-Greece