700635. Find n/k th node in Linked list
Here is a detailed Markdown blog post for the problem "Find n/k th node in Linked list":
Find n/k th node in Linked list
Summary
Given a linked list and two integers n and k, find the n/kth node from the beginning of the linked list. This problem requires understanding of linked lists, traversal, and basic arithmetic operations.
Detailed Explanation
To solve this problem, we will use a simple approach: traverse the linked list until we reach the desired node. We will keep track of the current node and increment a counter whenever we move to the next node.
Here is a step-by-step breakdown:
- Initialize a variable
countto 0 and a pointercurrentto the head of the linked list. - Traverse the linked list until
countis greater than or equal ton/k. - Increment
countby 1 for each node visited. - When
countis greater than or equal ton/k, return the current node.
To ensure we reach the correct node, we can maintain an additional variable k_count to keep track of how many nodes have been traversed so far. We increment this counter whenever we move to the next node and reset it when we find a new multiple of k. This ensures that we don't miss any nodes.
Here's a diagram illustrating the traversal:
Head -> Node 1 -> Node 2 -> ... -> Node n/k
^ ^
| |
k_count = 0
Time complexity: O(n) as we need to traverse the linked list once. Space complexity: O(1) as we only use a constant amount of space to store the variables.
Optimized Solutions
Java
public Node findNthNode(Node head, int n, int k) {
Node current = head;
int count = 0;
int k_count = 0;
while (current != null) {
count++;
if (count % k == 0) k_count++;
if (k_count == n) return current;
current = current.next;
}
return null; // not found
}