Grokking the Coding Interview: Patterns for Coding Questions
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Problem Challenge 1: Reverse alternating K-element Sub-list (medium)

Problem Statement

Given the head of a LinkedList and a number k, reverse every alternating k sized sub-list starting from the head.

The first k nodes are reversed, the next k are left alone, the next k are reversed, and so on. If the last group holds fewer than k nodes, treat it the same way as a full group: reverse it if it falls on a reversing turn, leave it alone if it falls on a skipping turn.

Example:

Input:  1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 10 -> null,  k = 3
Output: 3 -> 2 -> 1 -> 4 -> 5 -> 6 -> 9 -> 8 -> 7 -> 10 -> null

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dos

· 22 days ago

Why my saved code just disappeared ? seems you have TTL for the code submitted. is there any way to restore ?

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Shaho Shahbazpanahi

Shaho Shahbazpanahi

· a year ago

For this input [1,2,3,4,5,6,7,8,9,10,11] and k= 3, then expected output should be [3,2,1,6, 5, 4,10, 8,9,11, 10] while the solution give us [3,2,1,6, 5, 4,10, 8,9, 10, 11] , the problem stats if the rest of lis is smaller than k, revese it to .

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L

Lucas

· 4 years ago

Here is my solution! Hope it doesnt crack under pressure :) Image

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