How do you solve Nested Array Generator on LeetCode?

Nested Array Generator (LeetCode #2649) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(d) space complexity. Key insight: Using generators allows for efficient memory usage, especially with large nested structures.

What is the brute force solution for Nested Array Generator?

The brute force approach for Nested Array Generator is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute-force approach involves flattening the multi-dimensional array into a single list of integers. This is straightforward but inefficient as it creates a new array and requires multiple passes over the data. The optimal Optimal Solution approach improves this to O(n).

What are the interview tips for Nested Array Generator?

Explain your thought process clearly while coding. Consider edge cases and test your code with them. Practice writing recursive functions to become comfortable with them.

What are common mistakes when solving Nested Array Generator?

Not handling edge cases like empty arrays correctly. Forgetting to yield from recursive calls, leading to incomplete results.

#2649

Nested Array Generator

Medium

RecursionGenerator Functions

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(n)
Space	O(1)	O(d)

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Intuition

Time O(n)Space O(d)

The optimal solution uses a generator function that recursively yields integers directly from the nested structure without creating an intermediate list. This is efficient in terms of both time and space.

⚙️

Algorithm

4 steps

1Step 1: Define a generator function that takes the multi-dimensional array as input.
2Step 2: Iterate through each element of the array.
3Step 3: If the element is an integer, yield it. If it's an array, recursively call the generator function.
4Step 4: The generator will yield integers in the same order as they are encountered.

solution.py9 lines

1# Full working Python code
2
3def inorderTraversal(arr):
4    for item in arr:
5        if isinstance(item, int):
6            yield item
7        else:
8            yield from inorderTraversal(item)
9

ℹ

Complexity note: The time complexity is O(n) because we visit each element exactly once. The space complexity is O(d) where d is the maximum depth of the nested arrays, due to the call stack used in recursion.

1Using generators allows for efficient memory usage, especially with large nested structures.
2Recursive functions can simplify the traversal of nested data structures.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.