Adobe 面试真题解析｜Round-Robin Load Balancer 服务器分配算法（ VO 题） – 一亩三分地

Problem Description — Load Balancer

Implement a prototype round-robin load balancing algorithm for n servers, numbered from 1 to n, handling m incoming requests.

Each request i:

• arrives at time arrival[i]
• takes burstTime[i] time units to execute

Server Assignment Rules

• When a request arrives, it is assigned to the available server with the lowest index
• Once assigned, a server becomes unavailable from
  arrival[i] to arrival[i] + burstTime[i]
• If multiple requests arrive at the same time, they are processed in order of their original indices
• If no server is available at the arrival time, the request is dropped and assigned -1

Output Requirement

For each request, return:

• the 1-based index of the server that processes it
• or -1 if the request is dropped

Function Description

Complete the function:

getServerIndex(n, arrival, burstTime)

Parameters

• int n
  Number of servers
• int arrival[m]
  Arrival times of requests
• int burstTime[m]
  Execution time for each request

Returns

• int[m]
  Array where each element is:
  • the 1-based server index
  • or -1 if no server is available

Example

n = 3
arrival = [2, 4, 1, 8, 9]
burstTime = [7, 9, 2, 4, 5]

Request Processing Order (by arrival time)

Output

[2, 1, 1, 3, 2]

Constraints

• 1 ≤ n ≤ 10^5
• 1 ≤ m ≤ 10^5
• 1 ≤ arrival[i] ≤ 10^9
• 1 ≤ burstTime[i] ≤ 10^9

典型的系统设计 + 数据结构结合题 ，核心考察：

• 时间线模拟能力
• 可用资源管理（服务器池）
• 对「并发 + 排序规则」的理解