Feature #3: Find Story ID

Description

This feature will allow us to watch or re-watch stories on Instagram that are uploaded through Facebook. Every story uploaded by a user on Facebook gets assigned a unique incrementing id. On Instagram, a user can only watch one story at a time. These stories will be accessed from Facebook in ascending id order. When a story is watched, the story array rotates to accommodate unwatched stories at the start and watched stories at the end. Since stories are fetched from Facebook, so whenever a user wants to rewatch a story on Instagram, our system has to search for its id in the Facebook story list.

Observe this behavior in the illustration below:

We’ll have an array containing the story id’s. Some of the stories will be watched and will be at the end of the array, and some will be unwatched and will be at the start of the array. If a user clicks a story, we need to search for its id in the array and return the index of that id.

Solution

The solution is ...