Software Engineer, Front End

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Implement a SnapshotArray that supports the following interface: SnapshotArray(int length) initializes an array-like data structure with the given length. Initially, each element equals 0. void set(index, val) sets the element at the given index to be equal to val. int snap() takes a snapshot of the array and returns the snap_id: the total number of times we called snap() minus 1. int get(index, snap_id) returns the value at the given index, at the time we took the snapshot with the given snap_id For example: Input: [SnapshotArray,set,snap,set,get] [[3],[0,5],[],[0,6],[0,0]] Output: [null,null,0,null,5] Explanation: SnapshotArray snapshotArr = new SnapshotArray(3); // set the length to be 3 snapshotArr.set(0,5); // Set array[0] = 5 snapshotArr.snap(); // Take a snapshot, return snap_id = 0 snapshotArr.set(0,6); snapshotArr.get(0,0); // Get the value of array[0] with snap_id = 0, return 5 What data structures and algorithms are best suited for this problem? What are the time and space complexities of each operation?

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Let's design a new feature for the Facebook app: Ephemeral Groups. These groups function like regular Facebook groups but with a key difference: all content (posts, comments, media) within the group is automatically deleted after 24 hours. The group itself remains, but the content vanishes. Imagine users creating groups for flash events, temporary project collaborations, or just sharing memes that are only funny for a day. Here are some considerations to guide our design: Use Cases: What are the primary use cases for Ephemeral Groups? Consider examples beyond those mentioned above. User Interface: How would users create and identify Ephemeral Groups within the existing Facebook app? How is it visually distinct? Data Storage: How would you efficiently store and automatically delete content to minimize storage costs and ensure compliance with the 24-hour expiration? Abuse Prevention: How do you prevent the misuse of Ephemeral Groups for sharing harmful or illegal content, given the disappearing nature of the data? Notifications: How would notifications work for Ephemeral Groups? Should users receive notifications for content that will disappear soon? Privacy: How would we make users aware of the ephemeral nature of the group and its content to manage their privacy expectations effectively? Scalability: How would this feature scale to handle potentially millions of Ephemeral Groups without impacting the performance of the overall Facebook platform? Walk me through your design proposal, addressing these considerations and any other relevant aspects you believe are important.

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Where are you from in the US?