No One Left Behind

A medium Python interview practice problem on DataDriven. Write and execute real python code with instant grading.

Domain

Python

Difficulty

medium

Seniority

L4

Problem

You're reconciling two exported tables given as lists of dicts, `left` and `right`, that share a `key` field: combine them the way a SQL left join does, keeping every `left` record and merging in the fields of the first `right` record that shares its `key`. Every output row must expose the same right-side columns (every field name appearing anywhere in `right`, except the join `key`), so an unmatched row, or a match that lacks one of those fields, carries `None` there.

Summary

Every record stays; fill the gaps where a match exists.

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