LeetCode in Kotlin

2649. Nested Array Generator

Medium

Given a multi-dimensional array of integers, return a generator object which yields integers in the same order as inorder traversal.

A multi-dimensional array is a recursive data structure that contains both integers and other multi-dimensional arrays.

inorder traversal iterates over each array from left to right, yielding any integers it encounters or applying inorder traversal to any arrays it encounters.

Example 1:

Input: arr = [[[6]],[1,3],[]]

Output: [6,1,3]

Explanation:

const generator = inorderTraversal(arr); 
generator.next().value; // 6 
generator.next().value; // 1 
generator.next().value; // 3 
generator.next().done; // true

Example 2:

Input: arr = []

Output: []

Explanation: There are no integers so the generator doesn’t yield anything.

Constraints:

• 0 <= arr.flat().length <= 105
• 0 <= arr.flat()[i] <= 105
• maxNestingDepth <= 105

Can you solve this without creating a new flattened version of the array?

Solution

type MultidimensionalArray = (MultidimensionalArray | number)[]

function* inorderTraversal(arr: MultidimensionalArray): Generator<number, void, unknown> {
    for (const item of arr)
        if (Array.isArray(item)) yield* inorderTraversal(item)
        else yield item
}

/*
 * const gen = inorderTraversal([1, [2, 3]]);
 * gen.next().value; // 1
 * gen.next().value; // 2
 * gen.next().value; // 3
 */

export { inorderTraversal }

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