Reverse Nodes in K-Groups
Mastery
Reverse the nodes of the list k at a time and return the head. If the number of nodes left at the end is less than k, leave that last group as it is. Change the pointers, not the values.
For 1 -> 2 -> 3 -> 4 -> 5 and k = 2 the answer is 2 -> 1 -> 4 -> 3 -> 5.
The tests show a list as a Python list of its values: [1, 2, 3] stands for 1 -> 2 -> 3.
Examples
Example 1
Input:
reverse_k_group(head, 2) # head = 1 -> 2 -> 3 -> 4 -> 5
Output:
[2, 1, 4, 3, 5]
Example 2
Input:
reverse_k_group(head, 3) # head = 1 -> 2 -> 3 -> 4 -> 5
Output:
[3, 2, 1, 4, 5]
Constraints
0 <= number of nodes <= 1000001 <= k <= 100000
Theory
Go to TheoryKeywords
dsa-sheetlinked-listpointer-tricks
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