PROBLEM DESCRIPTION
You are given the head of a linked list and two integers m and n.
Traverse the linked list and remove some nodes in the following way:
- Start with the head as the current node.
- Keep the first m nodes starting with the current node.
- Remove the next n nodes
- Keep repeating steps 2 and 3 until you reach the end of the list.
Return the head of the modified list after removing the mentioned nodes.
SOLUTION
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode() {}
* ListNode(int val) { this.val = val; }
* ListNode(int val, ListNode next) { this.val = val; this.next = next; }
* }
*/
class Solution {
public ListNode deleteNodes(ListNode head, int m, int n) {
// Initialize two pointers, p1 and p2, to traverse the linked list.
ListNode p1 = head;
ListNode p2 = head;
// Start iterating through the linked list with p1.
while (p1 != null) {
// Keep the first m nodes starting with the current node.
for (int i = 0; i < m - 1; i++) {
// Move p1 to the next node if it's not null.
if (p1 == null) break;
p1 = p1.next;
}
// Remove the next n nodes.
p2 = p1;
for (int i = 0; i < n + 1; i++) {
// Move p2 to the next node if it's not null.
if (p2 == null) break;
p2 = p2.next;
}
// If p1 is not null, connect p1 to the node after p2 (effectively removing n nodes).
if (p1 != null) p1.next = p2;
// Move p1 to the new position after removing the nodes.
p1 = p2;
}
// Return the head of the modified linked list after processing.
return head;
}
}