Flatten Nested Array

A Closer Look at Functionsmedium

Course · Section 10: A Closer Look at Functions · Lecture 137: First-Class and Higher-Order Functions

Implement `flattenDeep(arr)` that recursively flattens a deeply nested array into a single flat array.

Input: flattenDeep([1,[2,[3,[4]]]])

Output: [1,2,3,4]

Input: flattenDeep([1,2,3])

Output: [1,2,3]

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Common pitfalls

Approach & explanation (try first)

Recursing into nested arrays and gathering non-array values flattens arbitrarily deep structures.

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