ZipRecruiter OA 四題全過 | 全流程復盤 程式設計邏輯題詳解 + 高分通關技巧

最近剛結束 ZipRecruiter 的 2026 NG OA，是那種「分級解鎖」題型——做完第 1 題才能看到第 2 題。 我這次四題全 AC，整體難度中等偏易，但邏輯抽象、實現要嚴謹。 下面是詳細復盤 + 改過的新題數據版本，想準備 OA 的同學可以直接參考。

ZipRecruiter OA 概覽

Level 1 – Basic CRUD Operations

Problem Description

Implement a basic in-memory database that supports the following operations:

set(key: str, field: str, value: str) -> None
get(key: str, field: str) -> str | None
delete(key: str, field: str) -> bool

Requirements:

• Each record is identified by a unique key.
• Each record contains multiple field-value pairs.
• set() inserts or updates the field.
• get() retrieves the value if it exists.
• delete() removes the field if it exists and returns a boolean.

Example (with updated data)

Level 2 – Scanning and Prefix Filtering

Problem Description

Extend your in-memory database to support listing fields and filtering by prefix.

scan(key: str) -> list[str]
scan_by_prefix(key: str, prefix: str) -> list[str]

Requirements:

• scan() returns all fields for a given key in lexicographic order.
• scan_by_prefix() returns only fields starting with the given prefix.
• The output format should be:
  ["()", ...]

Example (with updated data)

Level 3 – Timestamps and TTL Management

Problem Description

Introduce timestamps and Time-To-Live (TTL) logic for all data operations.
Each operation now includes a timestamp parameter, and records with TTLs should expire after their valid period.

New Methods:

set_at(key: str, field: str, value: str, timestamp: int) -> None
set_at_with_ttl(key: str, field: str, value: str, timestamp: int, ttl: int) -> None
get_at(key: str, field: str, timestamp: int) -> str | None
delete_at(key: str, field: str, timestamp: int) -> bool

Example (updated dataset)

Implementation Notes:

• Each field can be represented as:

db[key][field] = {"val": value, "start": timestamp, "ttl": ttl or None}

Expired when: current_timestamp >= start + ttl

Always clean up expired entries before every operation.

Level 4 – Backup and Restore Functionality

Problem Description

Add backup and restore features to maintain database snapshots over time.

New Methods:

backup(timestamp: int) -> int
restore(timestamp: int, timestamp_to_restore: int) -> None

Example (updated data)

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Jory Wang Amazon資深軟體開發工程師

Amazon 資深工程師，專注 基礎設施核心系統研發，在系統可擴充套件性、可靠性及成本最佳化方面具備豐富實戰經驗。 目前聚焦 FAANG SDE 面試輔導，一年內助力 30+ 位候選人成功斬獲 L5 / L6 Offer。

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