1. Ensuring Data Consistency in a Distributed Database

Your distributed database at TikTok needs to maintain data consistency across multiple nodes while supporting high availability. Which consistency model would best balance these requirements?

• Strong consistency
• Eventual consistency
• Weak consistency
• Read-your-writes consistency

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2. Optimizing Network Throughput in a Data Center

TikTok's data center needs to optimize network throughput to handle high volumes of data transfer between servers. Which network topology would best support this requirement?

• Bus topology
• Ring topology
• Star topology
• Fat-tree topology

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3. Enhancing Performance in a Virtualized Environment

Your team at TikTok needs to enhance the performance of applications running in a virtualized environment. Which technique would best achieve this goal?

• Overcommitting resources
• Using paravirtualization
• Implementing full virtualization
• Enabling nested virtualization

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4. Monitoring System Health in a Distributed Application

Monitoring the health and performance of your distributed application at TikTok is crucial for maintaining uptime and reliability. Which monitoring approach would best support this requirement?

• Centralized logging
• Polling-based monitoring
• Agent-based monitoring
• Passive monitoring

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5. Handling Deadlocks in a Distributed System

Your distributed system at TikTok occasionally encounters deadlocks due to multiple processes competing for resources. Which strategy would be most effective for preventing deadlocks in this distributed environment?

• Resource allocation graph
• Deadlock detection and recovery
• Banker's algorithm
• Wait-for graph

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6. TikTok Video ID Generation

TikTok is working to make the process of creating unique video IDs more efficient. A TikTok video ID is represented as a string called idStream of length n, made up of the digits '0' to '9'. TikTok also has a list called videoIds, which contains m target video ID strings, each also made up of digits '0' to '9'.

For each target video ID in videoIds, find the shortest part of idStream that contains all the characters needed to form any possible arrangement (permutation) of the target string.

You need to return an array of integers. The number at each position i in this array should be the length of the shortest part of idStream that can include all characters of the ith string in videoIds. If it’s impossible to create the target video ID from idStream, return -1 for that position.

Example
n = 12
idStream = "064819848398"
m = 3
videoIds = ["088", "364", "07"]

• To construct "088", the first 7 characters of the idStream ("064819848398") contain '0', '8', and '8'. Therefore, the answer for this target is 7.
• To construct "364", we need to access the first 10 characters of the idStream ("064819848398") and use the digits '6', '4', and '3'. By rearranging these digits to match "364", the answer is 10.
• For "07", there is no prefix in the idStream that contains both '0' and '7'. Thus, the answer is -1 for this target.

7. TikTok String Challenge

At the TikTok Academy, students are learning how to improve video captions.

You are given a string caption that only has small English letters ('a' to 'z'). You can make two kinds of changes to the caption at any letter as many times as needed:

1. Change the letter to the one right before it in the alphabet. You cannot change 'a' because it's already the first letter.
2. Change the letter to the one right after it in the alphabet. You cannot change 'z' because it's already the last letter.

For example, you can change 'f' to 'e' (the letter before) or 'g' (the letter after).

Your task is to make sure that every letter in the caption has at least one same letter next to it. For example, "aaabb" and "aaccdd" are good captions, but "abaaa" and "abcdef" are not.

Return the minimum number of changes needed to make the caption meet this rule.

Example
caption = "aca"

You can change 'c' to 'b' (the letter before), then to 'a' (the letter before). Now the caption is 'aaa', which meets the rule.

In total, you need 2 changes to meet the rule, which is minimum possible.

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